[06/15] drm/sun4i: tcon: Add support for tcon-top

Message ID	20180519183127.2718-7-jernej.skrabec@siol.net (mailing list archive)
State	New, archived
Headers	show Return-Path: <dri-devel-bounces@lists.freedesktop.org> sender: 031275009) by mail.siol.net (Postfix) with ESMTPSA id A6980520806; Sat, 19 May 2018 20:32:38 +0200 (CEST) From: Jernej Skrabec <jernej.skrabec@siol.net> To: maxime.ripard@bootlin.com, wens@csie.org, robh+dt@kernel.org Subject: [PATCH 06/15] drm/sun4i: tcon: Add support for tcon-top Date: Sat, 19 May 2018 20:31:18 +0200 Message-Id: <20180519183127.2718-7-jernej.skrabec@siol.net> In-Reply-To: <20180519183127.2718-1-jernej.skrabec@siol.net> References: <20180519183127.2718-1-jernej.skrabec@siol.net> Precedence: list Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-sunxi@googlegroups.com, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" <dri-devel-bounces@lists.freedesktop.org>

Jernej Škrabec May 19, 2018, 6:31 p.m. UTC

If SoC has TCON TOP unit, it has to be configured from TCON, since it
has all information needed. Additionally, if it is TCON TV, it must also
enable bus gate inside TCON TOP unit.

Add support for such TCONs.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 28 ++++++++++++++++++++++++++++
 drivers/gpu/drm/sun4i/sun4i_tcon.h |  8 ++++++++
 2 files changed, 36 insertions(+)

Jernej Škrabec May 21, 2018, 5:27 p.m. UTC | #1

Hi,

Dne ponedeljek, 21. maj 2018 ob 10:07:59 CEST je Maxime Ripard napisal(a):
> On Sat, May 19, 2018 at 08:31:18PM +0200, Jernej Skrabec wrote:
> > If SoC has TCON TOP unit, it has to be configured from TCON, since it
> > has all information needed. Additionally, if it is TCON TV, it must also
> > enable bus gate inside TCON TOP unit.
> 
> Why?

I'll explain my design decision below.

> 
> > Add support for such TCONs.
> > 
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > ---
> > 
> >  drivers/gpu/drm/sun4i/sun4i_tcon.c | 28 ++++++++++++++++++++++++++++
> >  drivers/gpu/drm/sun4i/sun4i_tcon.h |  8 ++++++++
> >  2 files changed, 36 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > b/drivers/gpu/drm/sun4i/sun4i_tcon.c index 08747fc3ee71..e0c562ce1c22
> > 100644
> > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > @@ -688,6 +688,16 @@ static int sun4i_tcon_init_clocks(struct device *dev,
> > 
> >  		dev_err(dev, "Couldn't get the TCON bus clock\n");
> >  		return PTR_ERR(tcon->clk);
> >  	
> >  	}
> > 
> > +
> > +	if (tcon->quirks->needs_tcon_top && tcon->quirks->has_channel_1) {
> > +		tcon->top_clk = devm_clk_get(dev, "tcon-top");
> > +		if (IS_ERR(tcon->top_clk)) {
> > +			dev_err(dev, "Couldn't get the TCON TOP bus clock\n");
> > +			return PTR_ERR(tcon->top_clk);
> > +		}
> > +		clk_prepare_enable(tcon->top_clk);
> > +	}
> > +
> > 
> >  	clk_prepare_enable(tcon->clk);
> >  	
> >  	if (tcon->quirks->has_channel_0) {
> > 
> > @@ -712,6 +722,7 @@ static int sun4i_tcon_init_clocks(struct device *dev,
> > 
> >  static void sun4i_tcon_free_clocks(struct sun4i_tcon *tcon)
> >  {
> >  
> >  	clk_disable_unprepare(tcon->clk);
> > 
> > +	clk_disable_unprepare(tcon->top_clk);
> > 
> >  }
> >  
> >  static int sun4i_tcon_init_irq(struct device *dev,
> > 
> > @@ -980,6 +991,23 @@ static int sun4i_tcon_bind(struct device *dev, struct
> > device *master,> 
> >  	tcon->id = engine->id;
> >  	tcon->quirks = of_device_get_match_data(dev);
> > 
> > +	if (tcon->quirks->needs_tcon_top) {
> > +		struct device_node *np;
> > +
> > +		np = of_parse_phandle(dev->of_node, "allwinner,tcon-top", 0);
> > +		if (np) {
> > +			struct platform_device *pdev;
> > +
> > +			pdev = of_find_device_by_node(np);
> > +			if (pdev)
> > +				tcon->tcon_top = platform_get_drvdata(pdev);
> > +			of_node_put(np);
> > +
> > +			if (!tcon->tcon_top)
> > +				return -EPROBE_DEFER;
> > +		}
> > +	}
> > +
> 
> I might have missed it, but I've not seen the bindings additions for
> that property. This shouldn't really be done that way anyway, instead
> of using a direct phandle, you should be using the of-graph, with the
> TCON-top sitting where it belongs in the flow of data.

Just to answer to the first question, it did describe it in "[PATCH 07/15] dt-
bindings: display: sun4i-drm: Add R40 HDMI pipeline".

As why I designed it that way - HW representation could be described that way 
(ASCII art makes sense when fixed width font is used to view it):

                            / LCD0/LVDS0
                / TCON-LCD0
                |           \ MIPI DSI
mixer0          |
       \        / TCON-LCD1 - LCD1/LVDS1
        TCON-TOP
       /        \ TCON-TV0 - TVE0/RGB
mixer1          |          \
                |           TCON-TOP - HDMI
                |          /
                \ TCON-TV1 - TVE1/RGB

This is a bit simplified, since there is also TVE-TOP, which is responsible 
for sharing 4 DACs between both TVE encoders. You can have two TV outs (PAL/
NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It even seems that you 
can arbitrarly choose which DAC is responsible for which signal, so there is a 
ton of possible end combinations, but I'm not 100% sure.

Even though I wrote TCON-TOP twice, this is same unit in HW. R40 manual 
suggest more possibilities, although some of them seem wrong, like RGB feeding 
from LCD TCON. That is confirmed to be wrong when checking BSP code. 

Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, TVE1 and LCD1 for 
pin muxing, although I'm not sure why is that needed at all, since according 
to R40 datasheet, TVE0 and TVE1 pins are dedicated and not on PORT D and PORT 
H, respectively, as TCON-TOP documentation suggest. However, HSYNC and PSYNC 
lines might be shared between TVE (when it works in RGB mode) and LCD. But 
that is just my guess since I'm not really familiar with RGB and LCD 
interfaces.

I'm really not sure what would be the best representation in OF-graph. Can you 
suggest one?

On the other hand, mux callback in TCON driver has all available informations 
at hand. It knows mixer ID, TCON ID and most importantly, encoder type. Based 
on all that informations, it's easy to configure TCON TOP.

I hope you understand. If you have better idea, I'm all ears, since phandle 
seems a bit weird to me too, but I think it's the only future proof, when 
adding LVDS, RGB, TVE or LCD support.

Best regards,
Jernej

Maxime Ripard May 24, 2018, 8:50 a.m. UTC | #2

On Mon, May 21, 2018 at 07:27:46PM +0200, Jernej Škrabec wrote:
> Hi,
> 
> Dne ponedeljek, 21. maj 2018 ob 10:07:59 CEST je Maxime Ripard napisal(a):
> > On Sat, May 19, 2018 at 08:31:18PM +0200, Jernej Skrabec wrote:
> > > If SoC has TCON TOP unit, it has to be configured from TCON, since it
> > > has all information needed. Additionally, if it is TCON TV, it must also
> > > enable bus gate inside TCON TOP unit.
> > 
> > Why?
> 
> I'll explain my design decision below.
> 
> > 
> > > Add support for such TCONs.
> > > 
> > > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > > ---
> > > 
> > >  drivers/gpu/drm/sun4i/sun4i_tcon.c | 28 ++++++++++++++++++++++++++++
> > >  drivers/gpu/drm/sun4i/sun4i_tcon.h |  8 ++++++++
> > >  2 files changed, 36 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > b/drivers/gpu/drm/sun4i/sun4i_tcon.c index 08747fc3ee71..e0c562ce1c22
> > > 100644
> > > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > > @@ -688,6 +688,16 @@ static int sun4i_tcon_init_clocks(struct device *dev,
> > > 
> > >  		dev_err(dev, "Couldn't get the TCON bus clock\n");
> > >  		return PTR_ERR(tcon->clk);
> > >  	
> > >  	}
> > > 
> > > +
> > > +	if (tcon->quirks->needs_tcon_top && tcon->quirks->has_channel_1) {
> > > +		tcon->top_clk = devm_clk_get(dev, "tcon-top");
> > > +		if (IS_ERR(tcon->top_clk)) {
> > > +			dev_err(dev, "Couldn't get the TCON TOP bus clock\n");
> > > +			return PTR_ERR(tcon->top_clk);
> > > +		}
> > > +		clk_prepare_enable(tcon->top_clk);
> > > +	}
> > > +
> > > 
> > >  	clk_prepare_enable(tcon->clk);
> > >  	
> > >  	if (tcon->quirks->has_channel_0) {
> > > 
> > > @@ -712,6 +722,7 @@ static int sun4i_tcon_init_clocks(struct device *dev,
> > > 
> > >  static void sun4i_tcon_free_clocks(struct sun4i_tcon *tcon)
> > >  {
> > >  
> > >  	clk_disable_unprepare(tcon->clk);
> > > 
> > > +	clk_disable_unprepare(tcon->top_clk);
> > > 
> > >  }
> > >  
> > >  static int sun4i_tcon_init_irq(struct device *dev,
> > > 
> > > @@ -980,6 +991,23 @@ static int sun4i_tcon_bind(struct device *dev, struct
> > > device *master,> 
> > >  	tcon->id = engine->id;
> > >  	tcon->quirks = of_device_get_match_data(dev);
> > > 
> > > +	if (tcon->quirks->needs_tcon_top) {
> > > +		struct device_node *np;
> > > +
> > > +		np = of_parse_phandle(dev->of_node, "allwinner,tcon-top", 0);
> > > +		if (np) {
> > > +			struct platform_device *pdev;
> > > +
> > > +			pdev = of_find_device_by_node(np);
> > > +			if (pdev)
> > > +				tcon->tcon_top = platform_get_drvdata(pdev);
> > > +			of_node_put(np);
> > > +
> > > +			if (!tcon->tcon_top)
> > > +				return -EPROBE_DEFER;
> > > +		}
> > > +	}
> > > +
> > 
> > I might have missed it, but I've not seen the bindings additions for
> > that property. This shouldn't really be done that way anyway, instead
> > of using a direct phandle, you should be using the of-graph, with the
> > TCON-top sitting where it belongs in the flow of data.
> 
> Just to answer to the first question, it did describe it in "[PATCH 07/15] dt-
> bindings: display: sun4i-drm: Add R40 HDMI pipeline".
> 
> As why I designed it that way - HW representation could be described that way 
> (ASCII art makes sense when fixed width font is used to view it):
> 
>                             / LCD0/LVDS0
>                 / TCON-LCD0
>                 |           \ MIPI DSI
> mixer0          |
>        \        / TCON-LCD1 - LCD1/LVDS1
>         TCON-TOP
>        /        \ TCON-TV0 - TVE0/RGB
> mixer1          |          \
>                 |           TCON-TOP - HDMI
>                 |          /
>                 \ TCON-TV1 - TVE1/RGB
> 
> This is a bit simplified, since there is also TVE-TOP, which is responsible 
> for sharing 4 DACs between both TVE encoders. You can have two TV outs (PAL/
> NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It even seems that you 
> can arbitrarly choose which DAC is responsible for which signal, so there is a 
> ton of possible end combinations, but I'm not 100% sure.
> 
> Even though I wrote TCON-TOP twice, this is same unit in HW. R40 manual 
> suggest more possibilities, although some of them seem wrong, like RGB feeding 
> from LCD TCON. That is confirmed to be wrong when checking BSP code. 
> 
> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, TVE1 and LCD1 for 
> pin muxing, although I'm not sure why is that needed at all, since according 
> to R40 datasheet, TVE0 and TVE1 pins are dedicated and not on PORT D and PORT 
> H, respectively, as TCON-TOP documentation suggest. However, HSYNC and PSYNC 
> lines might be shared between TVE (when it works in RGB mode) and LCD. But 
> that is just my guess since I'm not really familiar with RGB and LCD 
> interfaces.
> 
> I'm really not sure what would be the best representation in OF-graph. Can you 
> suggest one?

Rob might disagree on this one, but I don't see anything wrong with
having loops in the graph. If the TCON-TOP can be both the input and
output of the TCONs, then so be it, and have it described that way in
the graph.

The code is already able to filter out nodes that have already been
added to the list of devices we need to wait for in the component
framework, so that should work as well.

And we'd need to describe TVE-TOP as well, even though we don't have a
driver for it yet. That will simplify the backward compatibility later
on.

Maxime

Chen-Yu Tsai May 24, 2018, 10:01 p.m. UTC | #3

On Thu, May 24, 2018 at 1:50 AM, Maxime Ripard
<maxime.ripard@bootlin.com> wrote:
> On Mon, May 21, 2018 at 07:27:46PM +0200, Jernej Škrabec wrote:
>> Hi,
>>
>> Dne ponedeljek, 21. maj 2018 ob 10:07:59 CEST je Maxime Ripard napisal(a):
>> > On Sat, May 19, 2018 at 08:31:18PM +0200, Jernej Skrabec wrote:
>> > > If SoC has TCON TOP unit, it has to be configured from TCON, since it
>> > > has all information needed. Additionally, if it is TCON TV, it must also
>> > > enable bus gate inside TCON TOP unit.
>> >
>> > Why?
>>
>> I'll explain my design decision below.
>>
>> >
>> > > Add support for such TCONs.
>> > >
>> > > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
>> > > ---
>> > >
>> > >  drivers/gpu/drm/sun4i/sun4i_tcon.c | 28 ++++++++++++++++++++++++++++
>> > >  drivers/gpu/drm/sun4i/sun4i_tcon.h |  8 ++++++++
>> > >  2 files changed, 36 insertions(+)
>> > >
>> > > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c
>> > > b/drivers/gpu/drm/sun4i/sun4i_tcon.c index 08747fc3ee71..e0c562ce1c22
>> > > 100644
>> > > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
>> > > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
>> > > @@ -688,6 +688,16 @@ static int sun4i_tcon_init_clocks(struct device *dev,
>> > >
>> > >           dev_err(dev, "Couldn't get the TCON bus clock\n");
>> > >           return PTR_ERR(tcon->clk);
>> > >
>> > >   }
>> > >
>> > > +
>> > > + if (tcon->quirks->needs_tcon_top && tcon->quirks->has_channel_1) {
>> > > +         tcon->top_clk = devm_clk_get(dev, "tcon-top");
>> > > +         if (IS_ERR(tcon->top_clk)) {
>> > > +                 dev_err(dev, "Couldn't get the TCON TOP bus clock\n");
>> > > +                 return PTR_ERR(tcon->top_clk);
>> > > +         }
>> > > +         clk_prepare_enable(tcon->top_clk);
>> > > + }
>> > > +
>> > >
>> > >   clk_prepare_enable(tcon->clk);
>> > >
>> > >   if (tcon->quirks->has_channel_0) {
>> > >
>> > > @@ -712,6 +722,7 @@ static int sun4i_tcon_init_clocks(struct device *dev,
>> > >
>> > >  static void sun4i_tcon_free_clocks(struct sun4i_tcon *tcon)
>> > >  {
>> > >
>> > >   clk_disable_unprepare(tcon->clk);
>> > >
>> > > + clk_disable_unprepare(tcon->top_clk);
>> > >
>> > >  }
>> > >
>> > >  static int sun4i_tcon_init_irq(struct device *dev,
>> > >
>> > > @@ -980,6 +991,23 @@ static int sun4i_tcon_bind(struct device *dev, struct
>> > > device *master,>
>> > >   tcon->id = engine->id;
>> > >   tcon->quirks = of_device_get_match_data(dev);
>> > >
>> > > + if (tcon->quirks->needs_tcon_top) {
>> > > +         struct device_node *np;
>> > > +
>> > > +         np = of_parse_phandle(dev->of_node, "allwinner,tcon-top", 0);
>> > > +         if (np) {
>> > > +                 struct platform_device *pdev;
>> > > +
>> > > +                 pdev = of_find_device_by_node(np);
>> > > +                 if (pdev)
>> > > +                         tcon->tcon_top = platform_get_drvdata(pdev);
>> > > +                 of_node_put(np);
>> > > +
>> > > +                 if (!tcon->tcon_top)
>> > > +                         return -EPROBE_DEFER;
>> > > +         }
>> > > + }
>> > > +
>> >
>> > I might have missed it, but I've not seen the bindings additions for
>> > that property. This shouldn't really be done that way anyway, instead
>> > of using a direct phandle, you should be using the of-graph, with the
>> > TCON-top sitting where it belongs in the flow of data.
>>
>> Just to answer to the first question, it did describe it in "[PATCH 07/15] dt-
>> bindings: display: sun4i-drm: Add R40 HDMI pipeline".
>>
>> As why I designed it that way - HW representation could be described that way
>> (ASCII art makes sense when fixed width font is used to view it):
>>
>>                             / LCD0/LVDS0
>>                 / TCON-LCD0
>>                 |           \ MIPI DSI
>> mixer0          |
>>        \        / TCON-LCD1 - LCD1/LVDS1
>>         TCON-TOP
>>        /        \ TCON-TV0 - TVE0/RGB
>> mixer1          |          \
>>                 |           TCON-TOP - HDMI
>>                 |          /
>>                 \ TCON-TV1 - TVE1/RGB
>>
>> This is a bit simplified, since there is also TVE-TOP, which is responsible
>> for sharing 4 DACs between both TVE encoders. You can have two TV outs (PAL/
>> NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It even seems that you
>> can arbitrarly choose which DAC is responsible for which signal, so there is a
>> ton of possible end combinations, but I'm not 100% sure.
>>
>> Even though I wrote TCON-TOP twice, this is same unit in HW. R40 manual
>> suggest more possibilities, although some of them seem wrong, like RGB feeding
>> from LCD TCON. That is confirmed to be wrong when checking BSP code.
>>
>> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, TVE1 and LCD1 for
>> pin muxing, although I'm not sure why is that needed at all, since according
>> to R40 datasheet, TVE0 and TVE1 pins are dedicated and not on PORT D and PORT
>> H, respectively, as TCON-TOP documentation suggest. However, HSYNC and PSYNC
>> lines might be shared between TVE (when it works in RGB mode) and LCD. But
>> that is just my guess since I'm not really familiar with RGB and LCD
>> interfaces.
>>
>> I'm really not sure what would be the best representation in OF-graph. Can you
>> suggest one?
>
> Rob might disagree on this one, but I don't see anything wrong with
> having loops in the graph. If the TCON-TOP can be both the input and
> output of the TCONs, then so be it, and have it described that way in
> the graph.
>
> The code is already able to filter out nodes that have already been
> added to the list of devices we need to wait for in the component
> framework, so that should work as well.
>
> And we'd need to describe TVE-TOP as well, even though we don't have a
> driver for it yet. That will simplify the backward compatibility later
> on.

I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer that
binds everything together, and provides signal routing, kind of like
DE-TOP on A64. So the signal mux controls that were originally found
in TCON0 and TVE0 were moved out.

The driver needs to know about that, but the graph about doesn't make
much sense directly. Without looking at the manual, I understand it to
likely be one mux between the mixers and TCONs, and one between the
TCON-TVs and HDMI. Would it make more sense to just have the graph
connections between the muxed components, and remove TCON-TOP from
it, like we had in the past? A phandle could be used to reference
the TCON-TOP for mux controls, in addition to the clocks and resets.

For TVE, we would need something to represent each of the output pins,
so the device tree can actually describe what kind of signal, be it
each component of RGB/YUV or composite video, is wanted on each pin,
if any. This is also needed on the A20 for the Cubietruck, so we can
describe which pins are tied to the VGA connector, and which one does
R, G, or B.


Regards
ChenYu

Maxime Ripard May 31, 2018, 9:21 a.m. UTC | #4

On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
> >> > > + if (tcon->quirks->needs_tcon_top) {
> >> > > +         struct device_node *np;
> >> > > +
> >> > > +         np = of_parse_phandle(dev->of_node, "allwinner,tcon-top", 0);
> >> > > +         if (np) {
> >> > > +                 struct platform_device *pdev;
> >> > > +
> >> > > +                 pdev = of_find_device_by_node(np);
> >> > > +                 if (pdev)
> >> > > +                         tcon->tcon_top = platform_get_drvdata(pdev);
> >> > > +                 of_node_put(np);
> >> > > +
> >> > > +                 if (!tcon->tcon_top)
> >> > > +                         return -EPROBE_DEFER;
> >> > > +         }
> >> > > + }
> >> > > +
> >> >
> >> > I might have missed it, but I've not seen the bindings additions for
> >> > that property. This shouldn't really be done that way anyway, instead
> >> > of using a direct phandle, you should be using the of-graph, with the
> >> > TCON-top sitting where it belongs in the flow of data.
> >>
> >> Just to answer to the first question, it did describe it in "[PATCH 07/15] dt-
> >> bindings: display: sun4i-drm: Add R40 HDMI pipeline".
> >>
> >> As why I designed it that way - HW representation could be described that way
> >> (ASCII art makes sense when fixed width font is used to view it):
> >>
> >>                             / LCD0/LVDS0
> >>                 / TCON-LCD0
> >>                 |           \ MIPI DSI
> >> mixer0          |
> >>        \        / TCON-LCD1 - LCD1/LVDS1
> >>         TCON-TOP
> >>        /        \ TCON-TV0 - TVE0/RGB
> >> mixer1          |          \
> >>                 |           TCON-TOP - HDMI
> >>                 |          /
> >>                 \ TCON-TV1 - TVE1/RGB
> >>
> >> This is a bit simplified, since there is also TVE-TOP, which is responsible
> >> for sharing 4 DACs between both TVE encoders. You can have two TV outs (PAL/
> >> NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It even seems that you
> >> can arbitrarly choose which DAC is responsible for which signal, so there is a
> >> ton of possible end combinations, but I'm not 100% sure.
> >>
> >> Even though I wrote TCON-TOP twice, this is same unit in HW. R40 manual
> >> suggest more possibilities, although some of them seem wrong, like RGB feeding
> >> from LCD TCON. That is confirmed to be wrong when checking BSP code.
> >>
> >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, TVE1 and LCD1 for
> >> pin muxing, although I'm not sure why is that needed at all, since according
> >> to R40 datasheet, TVE0 and TVE1 pins are dedicated and not on PORT D and PORT
> >> H, respectively, as TCON-TOP documentation suggest. However, HSYNC and PSYNC
> >> lines might be shared between TVE (when it works in RGB mode) and LCD. But
> >> that is just my guess since I'm not really familiar with RGB and LCD
> >> interfaces.
> >>
> >> I'm really not sure what would be the best representation in OF-graph. Can you
> >> suggest one?
> >
> > Rob might disagree on this one, but I don't see anything wrong with
> > having loops in the graph. If the TCON-TOP can be both the input and
> > output of the TCONs, then so be it, and have it described that way in
> > the graph.
> >
> > The code is already able to filter out nodes that have already been
> > added to the list of devices we need to wait for in the component
> > framework, so that should work as well.
> >
> > And we'd need to describe TVE-TOP as well, even though we don't have a
> > driver for it yet. That will simplify the backward compatibility later
> > on.
> 
> I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer that
> binds everything together, and provides signal routing, kind of like
> DE-TOP on A64. So the signal mux controls that were originally found
> in TCON0 and TVE0 were moved out.
> 
> The driver needs to know about that, but the graph about doesn't make
> much sense directly. Without looking at the manual, I understand it to
> likely be one mux between the mixers and TCONs, and one between the
> TCON-TVs and HDMI. Would it make more sense to just have the graph
> connections between the muxed components, and remove TCON-TOP from
> it, like we had in the past? A phandle could be used to reference
> the TCON-TOP for mux controls, in addition to the clocks and resets.
> 
> For TVE, we would need something to represent each of the output pins,
> so the device tree can actually describe what kind of signal, be it
> each component of RGB/YUV or composite video, is wanted on each pin,
> if any. This is also needed on the A20 for the Cubietruck, so we can
> describe which pins are tied to the VGA connector, and which one does
> R, G, or B.

I guess we'll see how the DT maintainers feel about this, but my
impression is that the OF graph should model the flow of data between
the devices. If there's a mux somewhere, then the data is definitely
going through it, and as such it should be part of the graph.

Maxime

Jernej Škrabec May 31, 2018, 5:54 p.m. UTC | #5

Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard napisal(a):
> On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
> > >> > > + if (tcon->quirks->needs_tcon_top) {
> > >> > > +         struct device_node *np;
> > >> > > +
> > >> > > +         np = of_parse_phandle(dev->of_node, "allwinner,tcon-top",
> > >> > > 0);
> > >> > > +         if (np) {
> > >> > > +                 struct platform_device *pdev;
> > >> > > +
> > >> > > +                 pdev = of_find_device_by_node(np);
> > >> > > +                 if (pdev)
> > >> > > +                         tcon->tcon_top =
> > >> > > platform_get_drvdata(pdev);
> > >> > > +                 of_node_put(np);
> > >> > > +
> > >> > > +                 if (!tcon->tcon_top)
> > >> > > +                         return -EPROBE_DEFER;
> > >> > > +         }
> > >> > > + }
> > >> > > +
> > >> > 
> > >> > I might have missed it, but I've not seen the bindings additions for
> > >> > that property. This shouldn't really be done that way anyway, instead
> > >> > of using a direct phandle, you should be using the of-graph, with the
> > >> > TCON-top sitting where it belongs in the flow of data.
> > >> 
> > >> Just to answer to the first question, it did describe it in "[PATCH
> > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI pipeline".
> > >> 
> > >> As why I designed it that way - HW representation could be described
> > >> that way> >> 
> > >> (ASCII art makes sense when fixed width font is used to view it):
> > >>                             / LCD0/LVDS0
> > >>                 
> > >>                 / TCON-LCD0
> > >>                 
> > >>                 |           \ MIPI DSI
> > >> 
> > >> mixer0          |
> > >> 
> > >>        \        / TCON-LCD1 - LCD1/LVDS1
> > >>        
> > >>         TCON-TOP
> > >>        
> > >>        /        \ TCON-TV0 - TVE0/RGB
> > >> 
> > >> mixer1          |          \
> > >> 
> > >>                 |           TCON-TOP - HDMI
> > >>                 |          
> > >>                 |          /
> > >>                 
> > >>                 \ TCON-TV1 - TVE1/RGB
> > >> 
> > >> This is a bit simplified, since there is also TVE-TOP, which is
> > >> responsible
> > >> for sharing 4 DACs between both TVE encoders. You can have two TV outs
> > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It even
> > >> seems that you can arbitrarly choose which DAC is responsible for
> > >> which signal, so there is a ton of possible end combinations, but I'm
> > >> not 100% sure.
> > >> 
> > >> Even though I wrote TCON-TOP twice, this is same unit in HW. R40 manual
> > >> suggest more possibilities, although some of them seem wrong, like RGB
> > >> feeding from LCD TCON. That is confirmed to be wrong when checking BSP
> > >> code.
> > >> 
> > >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, TVE1 and
> > >> LCD1 for pin muxing, although I'm not sure why is that needed at all,
> > >> since according to R40 datasheet, TVE0 and TVE1 pins are dedicated and
> > >> not on PORT D and PORT H, respectively, as TCON-TOP documentation
> > >> suggest. However, HSYNC and PSYNC lines might be shared between TVE
> > >> (when it works in RGB mode) and LCD. But that is just my guess since
> > >> I'm not really familiar with RGB and LCD interfaces.
> > >> 
> > >> I'm really not sure what would be the best representation in OF-graph.
> > >> Can you suggest one?
> > > 
> > > Rob might disagree on this one, but I don't see anything wrong with
> > > having loops in the graph. If the TCON-TOP can be both the input and
> > > output of the TCONs, then so be it, and have it described that way in
> > > the graph.
> > > 
> > > The code is already able to filter out nodes that have already been
> > > added to the list of devices we need to wait for in the component
> > > framework, so that should work as well.
> > > 
> > > And we'd need to describe TVE-TOP as well, even though we don't have a
> > > driver for it yet. That will simplify the backward compatibility later
> > > on.
> > 
> > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer that
> > binds everything together, and provides signal routing, kind of like
> > DE-TOP on A64. So the signal mux controls that were originally found
> > in TCON0 and TVE0 were moved out.
> > 
> > The driver needs to know about that, but the graph about doesn't make
> > much sense directly. Without looking at the manual, I understand it to
> > likely be one mux between the mixers and TCONs, and one between the
> > TCON-TVs and HDMI. Would it make more sense to just have the graph
> > connections between the muxed components, and remove TCON-TOP from
> > it, like we had in the past? A phandle could be used to reference
> > the TCON-TOP for mux controls, in addition to the clocks and resets.
> > 
> > For TVE, we would need something to represent each of the output pins,
> > so the device tree can actually describe what kind of signal, be it
> > each component of RGB/YUV or composite video, is wanted on each pin,
> > if any. This is also needed on the A20 for the Cubietruck, so we can
> > describe which pins are tied to the VGA connector, and which one does
> > R, G, or B.
> 
> I guess we'll see how the DT maintainers feel about this, but my
> impression is that the OF graph should model the flow of data between
> the devices. If there's a mux somewhere, then the data is definitely
> going through it, and as such it should be part of the graph.

I concur, but I spent few days thinking how to represent this sanely in graph, 
but I didn't find any good solution. I'll represent here my idea and please 
tell your opinion before I start implementing it.

First, let me be clear that mixer0 and mixer1 don't have same capabilities 
(different number of planes, mixer0 supports writeback, mixer1 does not, 
etc.). Thus, it does matter which mixer is connected to which TCON/encoder. 
mixer0 is meant to be connected to main display and mixer1 to auxiliary. That 
obviously depends on end system.

So, TCON TOP has 3 muxes, which have to be represented in graph. Two of them 
are for mixer/TCON relationship (each of them 1 input and 4 possible outputs) 
and one for TV TCON/HDMI pair selection (2 possible inputs, 1 output).

According to current practice in sun4i-drm driver, graph has to have port 0, 
representing input and port 1, representing output. This would mean that graph 
looks something like that:

tcon_top: tcon-top@1c70000 {
	compatible = "allwinner,sun8i-r40-tcon-top";
	...
	ports {
		#address-cells = <1>;
		#size-cells = <0>;

		tcon_top_in: port@0 {
			#address-cells = <1>;
			#size-cells = <0>;
			reg = <0>;

			tcon_top_in_mixer0: endpoint@0 {
				reg = <0>;
				remote-endpoint = <&mixer0_out_tcon_top>;
			};

			tcon_top_in_mixer1: endpoint@1 {
				reg = <1>;
				remote-endpoint = <&mixer1_out_tcon_top>;
			};

			tcon_top_in_tcon_tv: endpoint@2 {
				reg = <2>;
				// here is HDMI input connection, part of board DTS
				remote-endpoint = <board specific phandle to TV TCON output>;
			};
		};

		tcon_top_out: port@1 {
			#address-cells = <1>;
			#size-cells = <0>;
			reg = <1>;

			tcon_top_out_tcon0: endpoint@0 {
				reg = <0>;
				// here is mixer0 output connection, part of board DTS
				remote-endpoint = <board specific phandle to TCON>;
			};

			tcon_top_out_tcon1: endpoint@1 {
				reg = <1>;
				// here is mixer1 output connection, part of board DTS
				remote-endpoint = <board specific phandle to TCON>;
			};

			tcon_top_out_hdmi: endpoint@2 {
				reg = <2>;
				remote-endpoint = <&hdmi_in_tcon_top>;
			};
		};
	};
};

tcon_tv0: lcd-controller@1c73000 {
	compatible = "allwinner,sun8i-r40-tcon-tv-0";
	...
	ports {
		#address-cells = <1>;
		#size-cells = <0>;

		tcon_tv0_in: port@0 {
			reg = <0>;

			tcon_tv0_in_tcon_top: endpoint {
				// endpoint depends on board, part of board DTS
				remote-endpoint = <phandle to one of tcon_top_out_tcon>;
			};
		};

		tcon_tv0_out: port@1 {
			#address-cells = <1>;
			#size-cells = <0>;
			reg = <1>;

			// endpoints to TV TOP and TCON TOP HDMI input
			...
		};
	};
};

tcon_tv1: lcd-controller@1c74000 {
	compatible = "allwinner,sun8i-r40-tcon-tv-1";
	...
	ports {
		#address-cells = <1>;
		#size-cells = <0>;

		tcon_tv1_in: port@0 {
			reg = <0>;

			tcon_tv1_in_tcon_top: endpoint {
				// endpoint depends on board, part of board DTS
				remote-endpoint = <phandle to one of tcon_top_out_tcon>;
			};
		};

		tcon_tv1_out: port@1 {
			#address-cells = <1>;
			#size-cells = <0>;
			reg = <1>;

			// endpoints to TV TOP and TCON TOP HDMI input
			...
		};
	};
};

tcon_lcd0 and tcon_lcd1 would have similar connections, except that for 
outputs would be LCD or LVDS panels or MIPI DSI encoder.

Please note that each TCON (there are 4 of them) would need to have unique 
compatible and have HW index stored in quirks data. It would be used by TCON 
TOP driver for configuring muxes.

What do you think about above suggestion?

Best regards,
Jernej

Maxime Ripard June 1, 2018, 3:29 p.m. UTC | #6

On Thu, May 31, 2018 at 07:54:08PM +0200, Jernej Škrabec wrote:
> Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard napisal(a):
> > On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
> > > >> > > + if (tcon->quirks->needs_tcon_top) {
> > > >> > > +         struct device_node *np;
> > > >> > > +
> > > >> > > +         np = of_parse_phandle(dev->of_node, "allwinner,tcon-top",
> > > >> > > 0);
> > > >> > > +         if (np) {
> > > >> > > +                 struct platform_device *pdev;
> > > >> > > +
> > > >> > > +                 pdev = of_find_device_by_node(np);
> > > >> > > +                 if (pdev)
> > > >> > > +                         tcon->tcon_top =
> > > >> > > platform_get_drvdata(pdev);
> > > >> > > +                 of_node_put(np);
> > > >> > > +
> > > >> > > +                 if (!tcon->tcon_top)
> > > >> > > +                         return -EPROBE_DEFER;
> > > >> > > +         }
> > > >> > > + }
> > > >> > > +
> > > >> > 
> > > >> > I might have missed it, but I've not seen the bindings additions for
> > > >> > that property. This shouldn't really be done that way anyway, instead
> > > >> > of using a direct phandle, you should be using the of-graph, with the
> > > >> > TCON-top sitting where it belongs in the flow of data.
> > > >> 
> > > >> Just to answer to the first question, it did describe it in "[PATCH
> > > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI pipeline".
> > > >> 
> > > >> As why I designed it that way - HW representation could be described
> > > >> that way> >> 
> > > >> (ASCII art makes sense when fixed width font is used to view it):
> > > >>                             / LCD0/LVDS0
> > > >>                 
> > > >>                 / TCON-LCD0
> > > >>                 
> > > >>                 |           \ MIPI DSI
> > > >> 
> > > >> mixer0          |
> > > >> 
> > > >>        \        / TCON-LCD1 - LCD1/LVDS1
> > > >>        
> > > >>         TCON-TOP
> > > >>        
> > > >>        /        \ TCON-TV0 - TVE0/RGB
> > > >> 
> > > >> mixer1          |          \
> > > >> 
> > > >>                 |           TCON-TOP - HDMI
> > > >>                 |          
> > > >>                 |          /
> > > >>                 
> > > >>                 \ TCON-TV1 - TVE1/RGB
> > > >> 
> > > >> This is a bit simplified, since there is also TVE-TOP, which is
> > > >> responsible
> > > >> for sharing 4 DACs between both TVE encoders. You can have two TV outs
> > > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It even
> > > >> seems that you can arbitrarly choose which DAC is responsible for
> > > >> which signal, so there is a ton of possible end combinations, but I'm
> > > >> not 100% sure.
> > > >> 
> > > >> Even though I wrote TCON-TOP twice, this is same unit in HW. R40 manual
> > > >> suggest more possibilities, although some of them seem wrong, like RGB
> > > >> feeding from LCD TCON. That is confirmed to be wrong when checking BSP
> > > >> code.
> > > >> 
> > > >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, TVE1 and
> > > >> LCD1 for pin muxing, although I'm not sure why is that needed at all,
> > > >> since according to R40 datasheet, TVE0 and TVE1 pins are dedicated and
> > > >> not on PORT D and PORT H, respectively, as TCON-TOP documentation
> > > >> suggest. However, HSYNC and PSYNC lines might be shared between TVE
> > > >> (when it works in RGB mode) and LCD. But that is just my guess since
> > > >> I'm not really familiar with RGB and LCD interfaces.
> > > >> 
> > > >> I'm really not sure what would be the best representation in OF-graph.
> > > >> Can you suggest one?
> > > > 
> > > > Rob might disagree on this one, but I don't see anything wrong with
> > > > having loops in the graph. If the TCON-TOP can be both the input and
> > > > output of the TCONs, then so be it, and have it described that way in
> > > > the graph.
> > > > 
> > > > The code is already able to filter out nodes that have already been
> > > > added to the list of devices we need to wait for in the component
> > > > framework, so that should work as well.
> > > > 
> > > > And we'd need to describe TVE-TOP as well, even though we don't have a
> > > > driver for it yet. That will simplify the backward compatibility later
> > > > on.
> > > 
> > > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer that
> > > binds everything together, and provides signal routing, kind of like
> > > DE-TOP on A64. So the signal mux controls that were originally found
> > > in TCON0 and TVE0 were moved out.
> > > 
> > > The driver needs to know about that, but the graph about doesn't make
> > > much sense directly. Without looking at the manual, I understand it to
> > > likely be one mux between the mixers and TCONs, and one between the
> > > TCON-TVs and HDMI. Would it make more sense to just have the graph
> > > connections between the muxed components, and remove TCON-TOP from
> > > it, like we had in the past? A phandle could be used to reference
> > > the TCON-TOP for mux controls, in addition to the clocks and resets.
> > > 
> > > For TVE, we would need something to represent each of the output pins,
> > > so the device tree can actually describe what kind of signal, be it
> > > each component of RGB/YUV or composite video, is wanted on each pin,
> > > if any. This is also needed on the A20 for the Cubietruck, so we can
> > > describe which pins are tied to the VGA connector, and which one does
> > > R, G, or B.
> > 
> > I guess we'll see how the DT maintainers feel about this, but my
> > impression is that the OF graph should model the flow of data between
> > the devices. If there's a mux somewhere, then the data is definitely
> > going through it, and as such it should be part of the graph.
> 
> I concur, but I spent few days thinking how to represent this sanely in graph, 
> but I didn't find any good solution. I'll represent here my idea and please 
> tell your opinion before I start implementing it.
> 
> First, let me be clear that mixer0 and mixer1 don't have same capabilities 
> (different number of planes, mixer0 supports writeback, mixer1 does not, 
> etc.). Thus, it does matter which mixer is connected to which TCON/encoder. 
> mixer0 is meant to be connected to main display and mixer1 to auxiliary. That 
> obviously depends on end system.
> 
> So, TCON TOP has 3 muxes, which have to be represented in graph. Two of them 
> are for mixer/TCON relationship (each of them 1 input and 4 possible outputs) 
> and one for TV TCON/HDMI pair selection (2 possible inputs, 1 output).
> 
> According to current practice in sun4i-drm driver, graph has to have port 0, 
> representing input and port 1, representing output. This would mean that graph 
> looks something like that:
> 
> tcon_top: tcon-top@1c70000 {
> 	compatible = "allwinner,sun8i-r40-tcon-top";
> 	...
> 	ports {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
> 
> 		tcon_top_in: port@0 {
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 			reg = <0>;
> 
> 			tcon_top_in_mixer0: endpoint@0 {
> 				reg = <0>;
> 				remote-endpoint = <&mixer0_out_tcon_top>;
> 			};
> 
> 			tcon_top_in_mixer1: endpoint@1 {
> 				reg = <1>;
> 				remote-endpoint = <&mixer1_out_tcon_top>;
> 			};
> 
> 			tcon_top_in_tcon_tv: endpoint@2 {
> 				reg = <2>;
> 				// here is HDMI input connection, part of board DTS
> 				remote-endpoint = <board specific phandle to TV TCON output>;
> 			};
> 		};
> 
> 		tcon_top_out: port@1 {
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 			reg = <1>;
> 
> 			tcon_top_out_tcon0: endpoint@0 {
> 				reg = <0>;
> 				// here is mixer0 output connection, part of board DTS
> 				remote-endpoint = <board specific phandle to TCON>;
> 			};
> 
> 			tcon_top_out_tcon1: endpoint@1 {
> 				reg = <1>;
> 				// here is mixer1 output connection, part of board DTS
> 				remote-endpoint = <board specific phandle to TCON>;
> 			};
> 
> 			tcon_top_out_hdmi: endpoint@2 {
> 				reg = <2>;
> 				remote-endpoint = <&hdmi_in_tcon_top>;
> 			};
> 		};
> 	};
> };

IIRC, each port is supposed to be one route for the data, so we would
have multiple ports, one for the mixers in input and for the tcon in
output, and one for the TCON in input and for the HDMI/TV in
output. Rob might correct me here.

> tcon_tv0: lcd-controller@1c73000 {
> 	compatible = "allwinner,sun8i-r40-tcon-tv-0";
> 	...
> 	ports {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
> 
> 		tcon_tv0_in: port@0 {
> 			reg = <0>;
> 
> 			tcon_tv0_in_tcon_top: endpoint {
> 				// endpoint depends on board, part of board DTS
> 				remote-endpoint = <phandle to one of tcon_top_out_tcon>;

Just curious, what would be there?

> 			};
> 		};
> 
> 		tcon_tv0_out: port@1 {
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 			reg = <1>;
> 
> 			// endpoints to TV TOP and TCON TOP HDMI input
> 			...
> 		};
> 	};
> };
> 
> tcon_tv1: lcd-controller@1c74000 {
> 	compatible = "allwinner,sun8i-r40-tcon-tv-1";
> 	...
> 	ports {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
> 
> 		tcon_tv1_in: port@0 {
> 			reg = <0>;
> 
> 			tcon_tv1_in_tcon_top: endpoint {
> 				// endpoint depends on board, part of board DTS
> 				remote-endpoint = <phandle to one of tcon_top_out_tcon>;
> 			};
> 		};
> 
> 		tcon_tv1_out: port@1 {
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 			reg = <1>;
> 
> 			// endpoints to TV TOP and TCON TOP HDMI input
> 			...
> 		};
> 	};
> };
> 
> tcon_lcd0 and tcon_lcd1 would have similar connections, except that for 
> outputs would be LCD or LVDS panels or MIPI DSI encoder.
> 
> Please note that each TCON (there are 4 of them) would need to have unique 
> compatible and have HW index stored in quirks data. It would be used by TCON 
> TOP driver for configuring muxes.

Can't we use the port/endpoint ID instead? If the mux is the only
thing that changes, the compatible has no reason to. It's the same IP,
and the only thing that changes is something that is not part of that
IP.

Maxime

Chen-Yu Tsai June 1, 2018, 4:19 p.m. UTC | #7

On Fri, Jun 1, 2018 at 8:29 AM, Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> On Thu, May 31, 2018 at 07:54:08PM +0200, Jernej Škrabec wrote:
>> Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard napisal(a):
>> > On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
>> > > >> > > + if (tcon->quirks->needs_tcon_top) {
>> > > >> > > +         struct device_node *np;
>> > > >> > > +
>> > > >> > > +         np = of_parse_phandle(dev->of_node, "allwinner,tcon-top",
>> > > >> > > 0);
>> > > >> > > +         if (np) {
>> > > >> > > +                 struct platform_device *pdev;
>> > > >> > > +
>> > > >> > > +                 pdev = of_find_device_by_node(np);
>> > > >> > > +                 if (pdev)
>> > > >> > > +                         tcon->tcon_top =
>> > > >> > > platform_get_drvdata(pdev);
>> > > >> > > +                 of_node_put(np);
>> > > >> > > +
>> > > >> > > +                 if (!tcon->tcon_top)
>> > > >> > > +                         return -EPROBE_DEFER;
>> > > >> > > +         }
>> > > >> > > + }
>> > > >> > > +
>> > > >> >
>> > > >> > I might have missed it, but I've not seen the bindings additions for
>> > > >> > that property. This shouldn't really be done that way anyway, instead
>> > > >> > of using a direct phandle, you should be using the of-graph, with the
>> > > >> > TCON-top sitting where it belongs in the flow of data.
>> > > >>
>> > > >> Just to answer to the first question, it did describe it in "[PATCH
>> > > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI pipeline".
>> > > >>
>> > > >> As why I designed it that way - HW representation could be described
>> > > >> that way> >>
>> > > >> (ASCII art makes sense when fixed width font is used to view it):
>> > > >>                             / LCD0/LVDS0
>> > > >>
>> > > >>                 / TCON-LCD0
>> > > >>
>> > > >>                 |           \ MIPI DSI
>> > > >>
>> > > >> mixer0          |
>> > > >>
>> > > >>        \        / TCON-LCD1 - LCD1/LVDS1
>> > > >>
>> > > >>         TCON-TOP
>> > > >>
>> > > >>        /        \ TCON-TV0 - TVE0/RGB
>> > > >>
>> > > >> mixer1          |          \
>> > > >>
>> > > >>                 |           TCON-TOP - HDMI
>> > > >>                 |
>> > > >>                 |          /
>> > > >>
>> > > >>                 \ TCON-TV1 - TVE1/RGB
>> > > >>
>> > > >> This is a bit simplified, since there is also TVE-TOP, which is
>> > > >> responsible
>> > > >> for sharing 4 DACs between both TVE encoders. You can have two TV outs
>> > > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It even
>> > > >> seems that you can arbitrarly choose which DAC is responsible for
>> > > >> which signal, so there is a ton of possible end combinations, but I'm
>> > > >> not 100% sure.
>> > > >>
>> > > >> Even though I wrote TCON-TOP twice, this is same unit in HW. R40 manual
>> > > >> suggest more possibilities, although some of them seem wrong, like RGB
>> > > >> feeding from LCD TCON. That is confirmed to be wrong when checking BSP
>> > > >> code.
>> > > >>
>> > > >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, TVE1 and
>> > > >> LCD1 for pin muxing, although I'm not sure why is that needed at all,
>> > > >> since according to R40 datasheet, TVE0 and TVE1 pins are dedicated and
>> > > >> not on PORT D and PORT H, respectively, as TCON-TOP documentation
>> > > >> suggest. However, HSYNC and PSYNC lines might be shared between TVE
>> > > >> (when it works in RGB mode) and LCD. But that is just my guess since
>> > > >> I'm not really familiar with RGB and LCD interfaces.
>> > > >>
>> > > >> I'm really not sure what would be the best representation in OF-graph.
>> > > >> Can you suggest one?
>> > > >
>> > > > Rob might disagree on this one, but I don't see anything wrong with
>> > > > having loops in the graph. If the TCON-TOP can be both the input and
>> > > > output of the TCONs, then so be it, and have it described that way in
>> > > > the graph.
>> > > >
>> > > > The code is already able to filter out nodes that have already been
>> > > > added to the list of devices we need to wait for in the component
>> > > > framework, so that should work as well.
>> > > >
>> > > > And we'd need to describe TVE-TOP as well, even though we don't have a
>> > > > driver for it yet. That will simplify the backward compatibility later
>> > > > on.
>> > >
>> > > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer that
>> > > binds everything together, and provides signal routing, kind of like
>> > > DE-TOP on A64. So the signal mux controls that were originally found
>> > > in TCON0 and TVE0 were moved out.
>> > >
>> > > The driver needs to know about that, but the graph about doesn't make
>> > > much sense directly. Without looking at the manual, I understand it to
>> > > likely be one mux between the mixers and TCONs, and one between the
>> > > TCON-TVs and HDMI. Would it make more sense to just have the graph
>> > > connections between the muxed components, and remove TCON-TOP from
>> > > it, like we had in the past? A phandle could be used to reference
>> > > the TCON-TOP for mux controls, in addition to the clocks and resets.
>> > >
>> > > For TVE, we would need something to represent each of the output pins,
>> > > so the device tree can actually describe what kind of signal, be it
>> > > each component of RGB/YUV or composite video, is wanted on each pin,
>> > > if any. This is also needed on the A20 for the Cubietruck, so we can
>> > > describe which pins are tied to the VGA connector, and which one does
>> > > R, G, or B.
>> >
>> > I guess we'll see how the DT maintainers feel about this, but my
>> > impression is that the OF graph should model the flow of data between
>> > the devices. If there's a mux somewhere, then the data is definitely
>> > going through it, and as such it should be part of the graph.
>>
>> I concur, but I spent few days thinking how to represent this sanely in graph,
>> but I didn't find any good solution. I'll represent here my idea and please
>> tell your opinion before I start implementing it.
>>
>> First, let me be clear that mixer0 and mixer1 don't have same capabilities
>> (different number of planes, mixer0 supports writeback, mixer1 does not,
>> etc.). Thus, it does matter which mixer is connected to which TCON/encoder.
>> mixer0 is meant to be connected to main display and mixer1 to auxiliary. That
>> obviously depends on end system.
>>
>> So, TCON TOP has 3 muxes, which have to be represented in graph. Two of them
>> are for mixer/TCON relationship (each of them 1 input and 4 possible outputs)
>> and one for TV TCON/HDMI pair selection (2 possible inputs, 1 output).
>>
>> According to current practice in sun4i-drm driver, graph has to have port 0,
>> representing input and port 1, representing output. This would mean that graph
>> looks something like that:
>>
>> tcon_top: tcon-top@1c70000 {
>>       compatible = "allwinner,sun8i-r40-tcon-top";
>>       ...
>>       ports {
>>               #address-cells = <1>;
>>               #size-cells = <0>;
>>
>>               tcon_top_in: port@0 {
>>                       #address-cells = <1>;
>>                       #size-cells = <0>;
>>                       reg = <0>;
>>
>>                       tcon_top_in_mixer0: endpoint@0 {
>>                               reg = <0>;
>>                               remote-endpoint = <&mixer0_out_tcon_top>;
>>                       };
>>
>>                       tcon_top_in_mixer1: endpoint@1 {
>>                               reg = <1>;
>>                               remote-endpoint = <&mixer1_out_tcon_top>;
>>                       };
>>
>>                       tcon_top_in_tcon_tv: endpoint@2 {
>>                               reg = <2>;
>>                               // here is HDMI input connection, part of board DTS
>>                               remote-endpoint = <board specific phandle to TV TCON output>;
>>                       };
>>               };
>>
>>               tcon_top_out: port@1 {
>>                       #address-cells = <1>;
>>                       #size-cells = <0>;
>>                       reg = <1>;
>>
>>                       tcon_top_out_tcon0: endpoint@0 {
>>                               reg = <0>;
>>                               // here is mixer0 output connection, part of board DTS
>>                               remote-endpoint = <board specific phandle to TCON>;
>>                       };
>>
>>                       tcon_top_out_tcon1: endpoint@1 {
>>                               reg = <1>;
>>                               // here is mixer1 output connection, part of board DTS
>>                               remote-endpoint = <board specific phandle to TCON>;
>>                       };
>>
>>                       tcon_top_out_hdmi: endpoint@2 {
>>                               reg = <2>;
>>                               remote-endpoint = <&hdmi_in_tcon_top>;
>>                       };
>>               };
>>       };
>> };
>
> IIRC, each port is supposed to be one route for the data, so we would
> have multiple ports, one for the mixers in input and for the tcon in
> output, and one for the TCON in input and for the HDMI/TV in
> output. Rob might correct me here.
>
>> tcon_tv0: lcd-controller@1c73000 {
>>       compatible = "allwinner,sun8i-r40-tcon-tv-0";
>>       ...
>>       ports {
>>               #address-cells = <1>;
>>               #size-cells = <0>;
>>
>>               tcon_tv0_in: port@0 {
>>                       reg = <0>;
>>
>>                       tcon_tv0_in_tcon_top: endpoint {
>>                               // endpoint depends on board, part of board DTS
>>                               remote-endpoint = <phandle to one of tcon_top_out_tcon>;
>
> Just curious, what would be there?
>
>>                       };
>>               };
>>
>>               tcon_tv0_out: port@1 {
>>                       #address-cells = <1>;
>>                       #size-cells = <0>;
>>                       reg = <1>;
>>
>>                       // endpoints to TV TOP and TCON TOP HDMI input
>>                       ...
>>               };
>>       };
>> };
>>
>> tcon_tv1: lcd-controller@1c74000 {
>>       compatible = "allwinner,sun8i-r40-tcon-tv-1";
>>       ...
>>       ports {
>>               #address-cells = <1>;
>>               #size-cells = <0>;
>>
>>               tcon_tv1_in: port@0 {
>>                       reg = <0>;
>>
>>                       tcon_tv1_in_tcon_top: endpoint {
>>                               // endpoint depends on board, part of board DTS
>>                               remote-endpoint = <phandle to one of tcon_top_out_tcon>;
>>                       };
>>               };
>>
>>               tcon_tv1_out: port@1 {
>>                       #address-cells = <1>;
>>                       #size-cells = <0>;
>>                       reg = <1>;
>>
>>                       // endpoints to TV TOP and TCON TOP HDMI input
>>                       ...
>>               };
>>       };
>> };
>>
>> tcon_lcd0 and tcon_lcd1 would have similar connections, except that for
>> outputs would be LCD or LVDS panels or MIPI DSI encoder.
>>
>> Please note that each TCON (there are 4 of them) would need to have unique
>> compatible and have HW index stored in quirks data. It would be used by TCON
>> TOP driver for configuring muxes.
>
> Can't we use the port/endpoint ID instead? If the mux is the only
> thing that changes, the compatible has no reason to. It's the same IP,
> and the only thing that changes is something that is not part of that
> IP.

I agree. Endpoint IDs should provide that information. I'm still not
sure How to encode multiple in/out mux groups in a device node though.

ChenYu

Maxime Ripard June 4, 2018, 11:50 a.m. UTC | #8

On Fri, Jun 01, 2018 at 09:19:43AM -0700, Chen-Yu Tsai wrote:
> On Fri, Jun 1, 2018 at 8:29 AM, Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> > On Thu, May 31, 2018 at 07:54:08PM +0200, Jernej Škrabec wrote:
> >> Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard napisal(a):
> >> > On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
> >> > > >> > > + if (tcon->quirks->needs_tcon_top) {
> >> > > >> > > +         struct device_node *np;
> >> > > >> > > +
> >> > > >> > > +         np = of_parse_phandle(dev->of_node, "allwinner,tcon-top",
> >> > > >> > > 0);
> >> > > >> > > +         if (np) {
> >> > > >> > > +                 struct platform_device *pdev;
> >> > > >> > > +
> >> > > >> > > +                 pdev = of_find_device_by_node(np);
> >> > > >> > > +                 if (pdev)
> >> > > >> > > +                         tcon->tcon_top =
> >> > > >> > > platform_get_drvdata(pdev);
> >> > > >> > > +                 of_node_put(np);
> >> > > >> > > +
> >> > > >> > > +                 if (!tcon->tcon_top)
> >> > > >> > > +                         return -EPROBE_DEFER;
> >> > > >> > > +         }
> >> > > >> > > + }
> >> > > >> > > +
> >> > > >> >
> >> > > >> > I might have missed it, but I've not seen the bindings additions for
> >> > > >> > that property. This shouldn't really be done that way anyway, instead
> >> > > >> > of using a direct phandle, you should be using the of-graph, with the
> >> > > >> > TCON-top sitting where it belongs in the flow of data.
> >> > > >>
> >> > > >> Just to answer to the first question, it did describe it in "[PATCH
> >> > > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI pipeline".
> >> > > >>
> >> > > >> As why I designed it that way - HW representation could be described
> >> > > >> that way> >>
> >> > > >> (ASCII art makes sense when fixed width font is used to view it):
> >> > > >>                             / LCD0/LVDS0
> >> > > >>
> >> > > >>                 / TCON-LCD0
> >> > > >>
> >> > > >>                 |           \ MIPI DSI
> >> > > >>
> >> > > >> mixer0          |
> >> > > >>
> >> > > >>        \        / TCON-LCD1 - LCD1/LVDS1
> >> > > >>
> >> > > >>         TCON-TOP
> >> > > >>
> >> > > >>        /        \ TCON-TV0 - TVE0/RGB
> >> > > >>
> >> > > >> mixer1          |          \
> >> > > >>
> >> > > >>                 |           TCON-TOP - HDMI
> >> > > >>                 |
> >> > > >>                 |          /
> >> > > >>
> >> > > >>                 \ TCON-TV1 - TVE1/RGB
> >> > > >>
> >> > > >> This is a bit simplified, since there is also TVE-TOP, which is
> >> > > >> responsible
> >> > > >> for sharing 4 DACs between both TVE encoders. You can have two TV outs
> >> > > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It even
> >> > > >> seems that you can arbitrarly choose which DAC is responsible for
> >> > > >> which signal, so there is a ton of possible end combinations, but I'm
> >> > > >> not 100% sure.
> >> > > >>
> >> > > >> Even though I wrote TCON-TOP twice, this is same unit in HW. R40 manual
> >> > > >> suggest more possibilities, although some of them seem wrong, like RGB
> >> > > >> feeding from LCD TCON. That is confirmed to be wrong when checking BSP
> >> > > >> code.
> >> > > >>
> >> > > >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0, TVE1 and
> >> > > >> LCD1 for pin muxing, although I'm not sure why is that needed at all,
> >> > > >> since according to R40 datasheet, TVE0 and TVE1 pins are dedicated and
> >> > > >> not on PORT D and PORT H, respectively, as TCON-TOP documentation
> >> > > >> suggest. However, HSYNC and PSYNC lines might be shared between TVE
> >> > > >> (when it works in RGB mode) and LCD. But that is just my guess since
> >> > > >> I'm not really familiar with RGB and LCD interfaces.
> >> > > >>
> >> > > >> I'm really not sure what would be the best representation in OF-graph.
> >> > > >> Can you suggest one?
> >> > > >
> >> > > > Rob might disagree on this one, but I don't see anything wrong with
> >> > > > having loops in the graph. If the TCON-TOP can be both the input and
> >> > > > output of the TCONs, then so be it, and have it described that way in
> >> > > > the graph.
> >> > > >
> >> > > > The code is already able to filter out nodes that have already been
> >> > > > added to the list of devices we need to wait for in the component
> >> > > > framework, so that should work as well.
> >> > > >
> >> > > > And we'd need to describe TVE-TOP as well, even though we don't have a
> >> > > > driver for it yet. That will simplify the backward compatibility later
> >> > > > on.
> >> > >
> >> > > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer that
> >> > > binds everything together, and provides signal routing, kind of like
> >> > > DE-TOP on A64. So the signal mux controls that were originally found
> >> > > in TCON0 and TVE0 were moved out.
> >> > >
> >> > > The driver needs to know about that, but the graph about doesn't make
> >> > > much sense directly. Without looking at the manual, I understand it to
> >> > > likely be one mux between the mixers and TCONs, and one between the
> >> > > TCON-TVs and HDMI. Would it make more sense to just have the graph
> >> > > connections between the muxed components, and remove TCON-TOP from
> >> > > it, like we had in the past? A phandle could be used to reference
> >> > > the TCON-TOP for mux controls, in addition to the clocks and resets.
> >> > >
> >> > > For TVE, we would need something to represent each of the output pins,
> >> > > so the device tree can actually describe what kind of signal, be it
> >> > > each component of RGB/YUV or composite video, is wanted on each pin,
> >> > > if any. This is also needed on the A20 for the Cubietruck, so we can
> >> > > describe which pins are tied to the VGA connector, and which one does
> >> > > R, G, or B.
> >> >
> >> > I guess we'll see how the DT maintainers feel about this, but my
> >> > impression is that the OF graph should model the flow of data between
> >> > the devices. If there's a mux somewhere, then the data is definitely
> >> > going through it, and as such it should be part of the graph.
> >>
> >> I concur, but I spent few days thinking how to represent this sanely in graph,
> >> but I didn't find any good solution. I'll represent here my idea and please
> >> tell your opinion before I start implementing it.
> >>
> >> First, let me be clear that mixer0 and mixer1 don't have same capabilities
> >> (different number of planes, mixer0 supports writeback, mixer1 does not,
> >> etc.). Thus, it does matter which mixer is connected to which TCON/encoder.
> >> mixer0 is meant to be connected to main display and mixer1 to auxiliary. That
> >> obviously depends on end system.
> >>
> >> So, TCON TOP has 3 muxes, which have to be represented in graph. Two of them
> >> are for mixer/TCON relationship (each of them 1 input and 4 possible outputs)
> >> and one for TV TCON/HDMI pair selection (2 possible inputs, 1 output).
> >>
> >> According to current practice in sun4i-drm driver, graph has to have port 0,
> >> representing input and port 1, representing output. This would mean that graph
> >> looks something like that:
> >>
> >> tcon_top: tcon-top@1c70000 {
> >>       compatible = "allwinner,sun8i-r40-tcon-top";
> >>       ...
> >>       ports {
> >>               #address-cells = <1>;
> >>               #size-cells = <0>;
> >>
> >>               tcon_top_in: port@0 {
> >>                       #address-cells = <1>;
> >>                       #size-cells = <0>;
> >>                       reg = <0>;
> >>
> >>                       tcon_top_in_mixer0: endpoint@0 {
> >>                               reg = <0>;
> >>                               remote-endpoint = <&mixer0_out_tcon_top>;
> >>                       };
> >>
> >>                       tcon_top_in_mixer1: endpoint@1 {
> >>                               reg = <1>;
> >>                               remote-endpoint = <&mixer1_out_tcon_top>;
> >>                       };
> >>
> >>                       tcon_top_in_tcon_tv: endpoint@2 {
> >>                               reg = <2>;
> >>                               // here is HDMI input connection, part of board DTS
> >>                               remote-endpoint = <board specific phandle to TV TCON output>;
> >>                       };
> >>               };
> >>
> >>               tcon_top_out: port@1 {
> >>                       #address-cells = <1>;
> >>                       #size-cells = <0>;
> >>                       reg = <1>;
> >>
> >>                       tcon_top_out_tcon0: endpoint@0 {
> >>                               reg = <0>;
> >>                               // here is mixer0 output connection, part of board DTS
> >>                               remote-endpoint = <board specific phandle to TCON>;
> >>                       };
> >>
> >>                       tcon_top_out_tcon1: endpoint@1 {
> >>                               reg = <1>;
> >>                               // here is mixer1 output connection, part of board DTS
> >>                               remote-endpoint = <board specific phandle to TCON>;
> >>                       };
> >>
> >>                       tcon_top_out_hdmi: endpoint@2 {
> >>                               reg = <2>;
> >>                               remote-endpoint = <&hdmi_in_tcon_top>;
> >>                       };
> >>               };
> >>       };
> >> };
> >
> > IIRC, each port is supposed to be one route for the data, so we would
> > have multiple ports, one for the mixers in input and for the tcon in
> > output, and one for the TCON in input and for the HDMI/TV in
> > output. Rob might correct me here.
> >
> >> tcon_tv0: lcd-controller@1c73000 {
> >>       compatible = "allwinner,sun8i-r40-tcon-tv-0";
> >>       ...
> >>       ports {
> >>               #address-cells = <1>;
> >>               #size-cells = <0>;
> >>
> >>               tcon_tv0_in: port@0 {
> >>                       reg = <0>;
> >>
> >>                       tcon_tv0_in_tcon_top: endpoint {
> >>                               // endpoint depends on board, part of board DTS
> >>                               remote-endpoint = <phandle to one of tcon_top_out_tcon>;
> >
> > Just curious, what would be there?
> >
> >>                       };
> >>               };
> >>
> >>               tcon_tv0_out: port@1 {
> >>                       #address-cells = <1>;
> >>                       #size-cells = <0>;
> >>                       reg = <1>;
> >>
> >>                       // endpoints to TV TOP and TCON TOP HDMI input
> >>                       ...
> >>               };
> >>       };
> >> };
> >>
> >> tcon_tv1: lcd-controller@1c74000 {
> >>       compatible = "allwinner,sun8i-r40-tcon-tv-1";
> >>       ...
> >>       ports {
> >>               #address-cells = <1>;
> >>               #size-cells = <0>;
> >>
> >>               tcon_tv1_in: port@0 {
> >>                       reg = <0>;
> >>
> >>                       tcon_tv1_in_tcon_top: endpoint {
> >>                               // endpoint depends on board, part of board DTS
> >>                               remote-endpoint = <phandle to one of tcon_top_out_tcon>;
> >>                       };
> >>               };
> >>
> >>               tcon_tv1_out: port@1 {
> >>                       #address-cells = <1>;
> >>                       #size-cells = <0>;
> >>                       reg = <1>;
> >>
> >>                       // endpoints to TV TOP and TCON TOP HDMI input
> >>                       ...
> >>               };
> >>       };
> >> };
> >>
> >> tcon_lcd0 and tcon_lcd1 would have similar connections, except that for
> >> outputs would be LCD or LVDS panels or MIPI DSI encoder.
> >>
> >> Please note that each TCON (there are 4 of them) would need to have unique
> >> compatible and have HW index stored in quirks data. It would be used by TCON
> >> TOP driver for configuring muxes.
> >
> > Can't we use the port/endpoint ID instead? If the mux is the only
> > thing that changes, the compatible has no reason to. It's the same IP,
> > and the only thing that changes is something that is not part of that
> > IP.
> 
> I agree. Endpoint IDs should provide that information. I'm still not
> sure How to encode multiple in/out mux groups in a device node though.

I guess we can do that through different ports?

Maxime

Jernej Škrabec June 4, 2018, 3:09 p.m. UTC | #9

Dne ponedeljek, 04. junij 2018 ob 13:50:34 CEST je Maxime Ripard napisal(a):
> On Fri, Jun 01, 2018 at 09:19:43AM -0700, Chen-Yu Tsai wrote:
> > On Fri, Jun 1, 2018 at 8:29 AM, Maxime Ripard <maxime.ripard@bootlin.com> 
wrote:
> > > On Thu, May 31, 2018 at 07:54:08PM +0200, Jernej Škrabec wrote:
> > >> Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard napisal(a):
> > >> > On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
> > >> > > >> > > + if (tcon->quirks->needs_tcon_top) {
> > >> > > >> > > +         struct device_node *np;
> > >> > > >> > > +
> > >> > > >> > > +         np = of_parse_phandle(dev->of_node,
> > >> > > >> > > "allwinner,tcon-top",
> > >> > > >> > > 0);
> > >> > > >> > > +         if (np) {
> > >> > > >> > > +                 struct platform_device *pdev;
> > >> > > >> > > +
> > >> > > >> > > +                 pdev = of_find_device_by_node(np);
> > >> > > >> > > +                 if (pdev)
> > >> > > >> > > +                         tcon->tcon_top =
> > >> > > >> > > platform_get_drvdata(pdev);
> > >> > > >> > > +                 of_node_put(np);
> > >> > > >> > > +
> > >> > > >> > > +                 if (!tcon->tcon_top)
> > >> > > >> > > +                         return -EPROBE_DEFER;
> > >> > > >> > > +         }
> > >> > > >> > > + }
> > >> > > >> > > +
> > >> > > >> > 
> > >> > > >> > I might have missed it, but I've not seen the bindings
> > >> > > >> > additions for
> > >> > > >> > that property. This shouldn't really be done that way anyway,
> > >> > > >> > instead
> > >> > > >> > of using a direct phandle, you should be using the of-graph,
> > >> > > >> > with the
> > >> > > >> > TCON-top sitting where it belongs in the flow of data.
> > >> > > >> 
> > >> > > >> Just to answer to the first question, it did describe it in
> > >> > > >> "[PATCH
> > >> > > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI pipeline".
> > >> > > >> 
> > >> > > >> As why I designed it that way - HW representation could be
> > >> > > >> described
> > >> > > >> that way> >>
> > >> > > >> 
> > >> > > >> (ASCII art makes sense when fixed width font is used to view 
it):
> > >> > > >>                             / LCD0/LVDS0
> > >> > > >>                 
> > >> > > >>                 / TCON-LCD0
> > >> > > >>                 
> > >> > > >>                 |           \ MIPI DSI
> > >> > > >> 
> > >> > > >> mixer0          |
> > >> > > >> 
> > >> > > >>        \        / TCON-LCD1 - LCD1/LVDS1
> > >> > > >>        
> > >> > > >>         TCON-TOP
> > >> > > >>        
> > >> > > >>        /        \ TCON-TV0 - TVE0/RGB
> > >> > > >> 
> > >> > > >> mixer1          |          \
> > >> > > >> 
> > >> > > >>                 |           TCON-TOP - HDMI
> > >> > > >>                 |          
> > >> > > >>                 |          /
> > >> > > >>                 
> > >> > > >>                 \ TCON-TV1 - TVE1/RGB
> > >> > > >> 
> > >> > > >> This is a bit simplified, since there is also TVE-TOP, which is
> > >> > > >> responsible
> > >> > > >> for sharing 4 DACs between both TVE encoders. You can have two
> > >> > > >> TV outs
> > >> > > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It
> > >> > > >> even
> > >> > > >> seems that you can arbitrarly choose which DAC is responsible
> > >> > > >> for
> > >> > > >> which signal, so there is a ton of possible end combinations,
> > >> > > >> but I'm
> > >> > > >> not 100% sure.
> > >> > > >> 
> > >> > > >> Even though I wrote TCON-TOP twice, this is same unit in HW. R40
> > >> > > >> manual
> > >> > > >> suggest more possibilities, although some of them seem wrong,
> > >> > > >> like RGB
> > >> > > >> feeding from LCD TCON. That is confirmed to be wrong when
> > >> > > >> checking BSP
> > >> > > >> code.
> > >> > > >> 
> > >> > > >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0,
> > >> > > >> TVE1 and
> > >> > > >> LCD1 for pin muxing, although I'm not sure why is that needed at
> > >> > > >> all,
> > >> > > >> since according to R40 datasheet, TVE0 and TVE1 pins are
> > >> > > >> dedicated and
> > >> > > >> not on PORT D and PORT H, respectively, as TCON-TOP
> > >> > > >> documentation
> > >> > > >> suggest. However, HSYNC and PSYNC lines might be shared between
> > >> > > >> TVE
> > >> > > >> (when it works in RGB mode) and LCD. But that is just my guess
> > >> > > >> since
> > >> > > >> I'm not really familiar with RGB and LCD interfaces.
> > >> > > >> 
> > >> > > >> I'm really not sure what would be the best representation in
> > >> > > >> OF-graph.
> > >> > > >> Can you suggest one?
> > >> > > > 
> > >> > > > Rob might disagree on this one, but I don't see anything wrong
> > >> > > > with
> > >> > > > having loops in the graph. If the TCON-TOP can be both the input
> > >> > > > and
> > >> > > > output of the TCONs, then so be it, and have it described that
> > >> > > > way in
> > >> > > > the graph.
> > >> > > > 
> > >> > > > The code is already able to filter out nodes that have already
> > >> > > > been
> > >> > > > added to the list of devices we need to wait for in the component
> > >> > > > framework, so that should work as well.
> > >> > > > 
> > >> > > > And we'd need to describe TVE-TOP as well, even though we don't
> > >> > > > have a
> > >> > > > driver for it yet. That will simplify the backward compatibility
> > >> > > > later
> > >> > > > on.
> > >> > > 
> > >> > > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer
> > >> > > that
> > >> > > binds everything together, and provides signal routing, kind of
> > >> > > like
> > >> > > DE-TOP on A64. So the signal mux controls that were originally
> > >> > > found
> > >> > > in TCON0 and TVE0 were moved out.
> > >> > > 
> > >> > > The driver needs to know about that, but the graph about doesn't
> > >> > > make
> > >> > > much sense directly. Without looking at the manual, I understand it
> > >> > > to
> > >> > > likely be one mux between the mixers and TCONs, and one between the
> > >> > > TCON-TVs and HDMI. Would it make more sense to just have the graph
> > >> > > connections between the muxed components, and remove TCON-TOP from
> > >> > > it, like we had in the past? A phandle could be used to reference
> > >> > > the TCON-TOP for mux controls, in addition to the clocks and
> > >> > > resets.
> > >> > > 
> > >> > > For TVE, we would need something to represent each of the output
> > >> > > pins,
> > >> > > so the device tree can actually describe what kind of signal, be it
> > >> > > each component of RGB/YUV or composite video, is wanted on each
> > >> > > pin,
> > >> > > if any. This is also needed on the A20 for the Cubietruck, so we
> > >> > > can
> > >> > > describe which pins are tied to the VGA connector, and which one
> > >> > > does
> > >> > > R, G, or B.
> > >> > 
> > >> > I guess we'll see how the DT maintainers feel about this, but my
> > >> > impression is that the OF graph should model the flow of data between
> > >> > the devices. If there's a mux somewhere, then the data is definitely
> > >> > going through it, and as such it should be part of the graph.
> > >> 
> > >> I concur, but I spent few days thinking how to represent this sanely in
> > >> graph, but I didn't find any good solution. I'll represent here my
> > >> idea and please tell your opinion before I start implementing it.
> > >> 
> > >> First, let me be clear that mixer0 and mixer1 don't have same
> > >> capabilities
> > >> (different number of planes, mixer0 supports writeback, mixer1 does
> > >> not,
> > >> etc.). Thus, it does matter which mixer is connected to which
> > >> TCON/encoder.
> > >> mixer0 is meant to be connected to main display and mixer1 to
> > >> auxiliary. That obviously depends on end system.
> > >> 
> > >> So, TCON TOP has 3 muxes, which have to be represented in graph. Two of
> > >> them are for mixer/TCON relationship (each of them 1 input and 4
> > >> possible outputs) and one for TV TCON/HDMI pair selection (2 possible
> > >> inputs, 1 output).
> > >> 
> > >> According to current practice in sun4i-drm driver, graph has to have
> > >> port 0, representing input and port 1, representing output. This would
> > >> mean that graph looks something like that:
> > >> 
> > >> tcon_top: tcon-top@1c70000 {
> > >> 
> > >>       compatible = "allwinner,sun8i-r40-tcon-top";
> > >>       ...
> > >>       ports {
> > >>       
> > >>               #address-cells = <1>;
> > >>               #size-cells = <0>;
> > >>               
> > >>               tcon_top_in: port@0 {
> > >>               
> > >>                       #address-cells = <1>;
> > >>                       #size-cells = <0>;
> > >>                       reg = <0>;
> > >>                       
> > >>                       tcon_top_in_mixer0: endpoint@0 {
> > >>                       
> > >>                               reg = <0>;
> > >>                               remote-endpoint = <&mixer0_out_tcon_top>;
> > >>                       
> > >>                       };
> > >>                       
> > >>                       tcon_top_in_mixer1: endpoint@1 {
> > >>                       
> > >>                               reg = <1>;
> > >>                               remote-endpoint = <&mixer1_out_tcon_top>;
> > >>                       
> > >>                       };
> > >>                       
> > >>                       tcon_top_in_tcon_tv: endpoint@2 {
> > >>                       
> > >>                               reg = <2>;
> > >>                               // here is HDMI input connection, part of
> > >>                               board DTS
> > >>                               remote-endpoint = <board specific phandle
> > >>                               to TV TCON output>;
> > >>                       
> > >>                       };
> > >>               
> > >>               };
> > >>               
> > >>               tcon_top_out: port@1 {
> > >>               
> > >>                       #address-cells = <1>;
> > >>                       #size-cells = <0>;
> > >>                       reg = <1>;
> > >>                       
> > >>                       tcon_top_out_tcon0: endpoint@0 {
> > >>                       
> > >>                               reg = <0>;
> > >>                               // here is mixer0 output connection, part
> > >>                               of board DTS
> > >>                               remote-endpoint = <board specific phandle
> > >>                               to TCON>;
> > >>                       
> > >>                       };
> > >>                       
> > >>                       tcon_top_out_tcon1: endpoint@1 {
> > >>                       
> > >>                               reg = <1>;
> > >>                               // here is mixer1 output connection, part
> > >>                               of board DTS
> > >>                               remote-endpoint = <board specific phandle
> > >>                               to TCON>;
> > >>                       
> > >>                       };
> > >>                       
> > >>                       tcon_top_out_hdmi: endpoint@2 {
> > >>                       
> > >>                               reg = <2>;
> > >>                               remote-endpoint = <&hdmi_in_tcon_top>;
> > >>                       
> > >>                       };
> > >>               
> > >>               };
> > >>       
> > >>       };
> > >> 
> > >> };
> > > 
> > > IIRC, each port is supposed to be one route for the data, so we would
> > > have multiple ports, one for the mixers in input and for the tcon in
> > > output, and one for the TCON in input and for the HDMI/TV in
> > > output. Rob might correct me here.

Ok, that seems more clean approach. I'll have to extend graph traversing 
algorithm in sun4i_drv.c, but that's no problem.

Just to be clear, you have in mind 3 pairs of ports (0/1 for mixer0 mux, 2/3 
for mixer1 and 4/5 for HDMI input), right? That way each mux is represented 
with one pair of ports, even numbered for input and odd numbered for output.

> > > 
> > >> tcon_tv0: lcd-controller@1c73000 {
> > >> 
> > >>       compatible = "allwinner,sun8i-r40-tcon-tv-0";
> > >>       ...
> > >>       ports {
> > >>       
> > >>               #address-cells = <1>;
> > >>               #size-cells = <0>;
> > >>               
> > >>               tcon_tv0_in: port@0 {
> > >>               
> > >>                       reg = <0>;
> > >>                       
> > >>                       tcon_tv0_in_tcon_top: endpoint {
> > >>                       
> > >>                               // endpoint depends on board, part of
> > >>                               board DTS
> > >>                               remote-endpoint = <phandle to one of
> > >>                               tcon_top_out_tcon>;
> > > 
> > > Just curious, what would be there?

Either phandle to tcon_top_out_tcon0 or tcon_top_out_tcon1.

> > > 
> > >>                       };
> > >>               
> > >>               };
> > >>               
> > >>               tcon_tv0_out: port@1 {
> > >>               
> > >>                       #address-cells = <1>;
> > >>                       #size-cells = <0>;
> > >>                       reg = <1>;
> > >>                       
> > >>                       // endpoints to TV TOP and TCON TOP HDMI input
> > >>                       ...
> > >>               
> > >>               };
> > >>       
> > >>       };
> > >> 
> > >> };
> > >> 
> > >> tcon_tv1: lcd-controller@1c74000 {
> > >> 
> > >>       compatible = "allwinner,sun8i-r40-tcon-tv-1";
> > >>       ...
> > >>       ports {
> > >>       
> > >>               #address-cells = <1>;
> > >>               #size-cells = <0>;
> > >>               
> > >>               tcon_tv1_in: port@0 {
> > >>               
> > >>                       reg = <0>;
> > >>                       
> > >>                       tcon_tv1_in_tcon_top: endpoint {
> > >>                       
> > >>                               // endpoint depends on board, part of
> > >>                               board DTS
> > >>                               remote-endpoint = <phandle to one of
> > >>                               tcon_top_out_tcon>;
> > >>                       
> > >>                       };
> > >>               
> > >>               };
> > >>               
> > >>               tcon_tv1_out: port@1 {
> > >>               
> > >>                       #address-cells = <1>;
> > >>                       #size-cells = <0>;
> > >>                       reg = <1>;
> > >>                       
> > >>                       // endpoints to TV TOP and TCON TOP HDMI input
> > >>                       ...
> > >>               
> > >>               };
> > >>       
> > >>       };
> > >> 
> > >> };
> > >> 
> > >> tcon_lcd0 and tcon_lcd1 would have similar connections, except that for
> > >> outputs would be LCD or LVDS panels or MIPI DSI encoder.
> > >> 
> > >> Please note that each TCON (there are 4 of them) would need to have
> > >> unique
> > >> compatible and have HW index stored in quirks data. It would be used by
> > >> TCON TOP driver for configuring muxes.
> > > 
> > > Can't we use the port/endpoint ID instead? If the mux is the only
> > > thing that changes, the compatible has no reason to. It's the same IP,
> > > and the only thing that changes is something that is not part of that
> > > IP.
> > 
> > I agree. Endpoint IDs should provide that information. I'm still not
> > sure How to encode multiple in/out mux groups in a device node though.
> 
> I guess we can do that through different ports?

Ok, I'll try to do something with "reg" property.

Best regards,
Jernej

Maxime Ripard June 4, 2018, 4:23 p.m. UTC | #10

On Mon, Jun 04, 2018 at 05:09:56PM +0200, Jernej Škrabec wrote:
> Dne ponedeljek, 04. junij 2018 ob 13:50:34 CEST je Maxime Ripard napisal(a):
> > On Fri, Jun 01, 2018 at 09:19:43AM -0700, Chen-Yu Tsai wrote:
> > > On Fri, Jun 1, 2018 at 8:29 AM, Maxime Ripard <maxime.ripard@bootlin.com> 
> wrote:
> > > > On Thu, May 31, 2018 at 07:54:08PM +0200, Jernej Škrabec wrote:
> > > >> Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard napisal(a):
> > > >> > On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
> > > >> > > >> > > + if (tcon->quirks->needs_tcon_top) {
> > > >> > > >> > > +         struct device_node *np;
> > > >> > > >> > > +
> > > >> > > >> > > +         np = of_parse_phandle(dev->of_node,
> > > >> > > >> > > "allwinner,tcon-top",
> > > >> > > >> > > 0);
> > > >> > > >> > > +         if (np) {
> > > >> > > >> > > +                 struct platform_device *pdev;
> > > >> > > >> > > +
> > > >> > > >> > > +                 pdev = of_find_device_by_node(np);
> > > >> > > >> > > +                 if (pdev)
> > > >> > > >> > > +                         tcon->tcon_top =
> > > >> > > >> > > platform_get_drvdata(pdev);
> > > >> > > >> > > +                 of_node_put(np);
> > > >> > > >> > > +
> > > >> > > >> > > +                 if (!tcon->tcon_top)
> > > >> > > >> > > +                         return -EPROBE_DEFER;
> > > >> > > >> > > +         }
> > > >> > > >> > > + }
> > > >> > > >> > > +
> > > >> > > >> > 
> > > >> > > >> > I might have missed it, but I've not seen the bindings
> > > >> > > >> > additions for
> > > >> > > >> > that property. This shouldn't really be done that way anyway,
> > > >> > > >> > instead
> > > >> > > >> > of using a direct phandle, you should be using the of-graph,
> > > >> > > >> > with the
> > > >> > > >> > TCON-top sitting where it belongs in the flow of data.
> > > >> > > >> 
> > > >> > > >> Just to answer to the first question, it did describe it in
> > > >> > > >> "[PATCH
> > > >> > > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI pipeline".
> > > >> > > >> 
> > > >> > > >> As why I designed it that way - HW representation could be
> > > >> > > >> described
> > > >> > > >> that way> >>
> > > >> > > >> 
> > > >> > > >> (ASCII art makes sense when fixed width font is used to view 
> it):
> > > >> > > >>                             / LCD0/LVDS0
> > > >> > > >>                 
> > > >> > > >>                 / TCON-LCD0
> > > >> > > >>                 
> > > >> > > >>                 |           \ MIPI DSI
> > > >> > > >> 
> > > >> > > >> mixer0          |
> > > >> > > >> 
> > > >> > > >>        \        / TCON-LCD1 - LCD1/LVDS1
> > > >> > > >>        
> > > >> > > >>         TCON-TOP
> > > >> > > >>        
> > > >> > > >>        /        \ TCON-TV0 - TVE0/RGB
> > > >> > > >> 
> > > >> > > >> mixer1          |          \
> > > >> > > >> 
> > > >> > > >>                 |           TCON-TOP - HDMI
> > > >> > > >>                 |          
> > > >> > > >>                 |          /
> > > >> > > >>                 
> > > >> > > >>                 \ TCON-TV1 - TVE1/RGB
> > > >> > > >> 
> > > >> > > >> This is a bit simplified, since there is also TVE-TOP, which is
> > > >> > > >> responsible
> > > >> > > >> for sharing 4 DACs between both TVE encoders. You can have two
> > > >> > > >> TV outs
> > > >> > > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa. It
> > > >> > > >> even
> > > >> > > >> seems that you can arbitrarly choose which DAC is responsible
> > > >> > > >> for
> > > >> > > >> which signal, so there is a ton of possible end combinations,
> > > >> > > >> but I'm
> > > >> > > >> not 100% sure.
> > > >> > > >> 
> > > >> > > >> Even though I wrote TCON-TOP twice, this is same unit in HW. R40
> > > >> > > >> manual
> > > >> > > >> suggest more possibilities, although some of them seem wrong,
> > > >> > > >> like RGB
> > > >> > > >> feeding from LCD TCON. That is confirmed to be wrong when
> > > >> > > >> checking BSP
> > > >> > > >> code.
> > > >> > > >> 
> > > >> > > >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0,
> > > >> > > >> TVE1 and
> > > >> > > >> LCD1 for pin muxing, although I'm not sure why is that needed at
> > > >> > > >> all,
> > > >> > > >> since according to R40 datasheet, TVE0 and TVE1 pins are
> > > >> > > >> dedicated and
> > > >> > > >> not on PORT D and PORT H, respectively, as TCON-TOP
> > > >> > > >> documentation
> > > >> > > >> suggest. However, HSYNC and PSYNC lines might be shared between
> > > >> > > >> TVE
> > > >> > > >> (when it works in RGB mode) and LCD. But that is just my guess
> > > >> > > >> since
> > > >> > > >> I'm not really familiar with RGB and LCD interfaces.
> > > >> > > >> 
> > > >> > > >> I'm really not sure what would be the best representation in
> > > >> > > >> OF-graph.
> > > >> > > >> Can you suggest one?
> > > >> > > > 
> > > >> > > > Rob might disagree on this one, but I don't see anything wrong
> > > >> > > > with
> > > >> > > > having loops in the graph. If the TCON-TOP can be both the input
> > > >> > > > and
> > > >> > > > output of the TCONs, then so be it, and have it described that
> > > >> > > > way in
> > > >> > > > the graph.
> > > >> > > > 
> > > >> > > > The code is already able to filter out nodes that have already
> > > >> > > > been
> > > >> > > > added to the list of devices we need to wait for in the component
> > > >> > > > framework, so that should work as well.
> > > >> > > > 
> > > >> > > > And we'd need to describe TVE-TOP as well, even though we don't
> > > >> > > > have a
> > > >> > > > driver for it yet. That will simplify the backward compatibility
> > > >> > > > later
> > > >> > > > on.
> > > >> > > 
> > > >> > > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue layer
> > > >> > > that
> > > >> > > binds everything together, and provides signal routing, kind of
> > > >> > > like
> > > >> > > DE-TOP on A64. So the signal mux controls that were originally
> > > >> > > found
> > > >> > > in TCON0 and TVE0 were moved out.
> > > >> > > 
> > > >> > > The driver needs to know about that, but the graph about doesn't
> > > >> > > make
> > > >> > > much sense directly. Without looking at the manual, I understand it
> > > >> > > to
> > > >> > > likely be one mux between the mixers and TCONs, and one between the
> > > >> > > TCON-TVs and HDMI. Would it make more sense to just have the graph
> > > >> > > connections between the muxed components, and remove TCON-TOP from
> > > >> > > it, like we had in the past? A phandle could be used to reference
> > > >> > > the TCON-TOP for mux controls, in addition to the clocks and
> > > >> > > resets.
> > > >> > > 
> > > >> > > For TVE, we would need something to represent each of the output
> > > >> > > pins,
> > > >> > > so the device tree can actually describe what kind of signal, be it
> > > >> > > each component of RGB/YUV or composite video, is wanted on each
> > > >> > > pin,
> > > >> > > if any. This is also needed on the A20 for the Cubietruck, so we
> > > >> > > can
> > > >> > > describe which pins are tied to the VGA connector, and which one
> > > >> > > does
> > > >> > > R, G, or B.
> > > >> > 
> > > >> > I guess we'll see how the DT maintainers feel about this, but my
> > > >> > impression is that the OF graph should model the flow of data between
> > > >> > the devices. If there's a mux somewhere, then the data is definitely
> > > >> > going through it, and as such it should be part of the graph.
> > > >> 
> > > >> I concur, but I spent few days thinking how to represent this sanely in
> > > >> graph, but I didn't find any good solution. I'll represent here my
> > > >> idea and please tell your opinion before I start implementing it.
> > > >> 
> > > >> First, let me be clear that mixer0 and mixer1 don't have same
> > > >> capabilities
> > > >> (different number of planes, mixer0 supports writeback, mixer1 does
> > > >> not,
> > > >> etc.). Thus, it does matter which mixer is connected to which
> > > >> TCON/encoder.
> > > >> mixer0 is meant to be connected to main display and mixer1 to
> > > >> auxiliary. That obviously depends on end system.
> > > >> 
> > > >> So, TCON TOP has 3 muxes, which have to be represented in graph. Two of
> > > >> them are for mixer/TCON relationship (each of them 1 input and 4
> > > >> possible outputs) and one for TV TCON/HDMI pair selection (2 possible
> > > >> inputs, 1 output).
> > > >> 
> > > >> According to current practice in sun4i-drm driver, graph has to have
> > > >> port 0, representing input and port 1, representing output. This would
> > > >> mean that graph looks something like that:
> > > >> 
> > > >> tcon_top: tcon-top@1c70000 {
> > > >> 
> > > >>       compatible = "allwinner,sun8i-r40-tcon-top";
> > > >>       ...
> > > >>       ports {
> > > >>       
> > > >>               #address-cells = <1>;
> > > >>               #size-cells = <0>;
> > > >>               
> > > >>               tcon_top_in: port@0 {
> > > >>               
> > > >>                       #address-cells = <1>;
> > > >>                       #size-cells = <0>;
> > > >>                       reg = <0>;
> > > >>                       
> > > >>                       tcon_top_in_mixer0: endpoint@0 {
> > > >>                       
> > > >>                               reg = <0>;
> > > >>                               remote-endpoint = <&mixer0_out_tcon_top>;
> > > >>                       
> > > >>                       };
> > > >>                       
> > > >>                       tcon_top_in_mixer1: endpoint@1 {
> > > >>                       
> > > >>                               reg = <1>;
> > > >>                               remote-endpoint = <&mixer1_out_tcon_top>;
> > > >>                       
> > > >>                       };
> > > >>                       
> > > >>                       tcon_top_in_tcon_tv: endpoint@2 {
> > > >>                       
> > > >>                               reg = <2>;
> > > >>                               // here is HDMI input connection, part of
> > > >>                               board DTS
> > > >>                               remote-endpoint = <board specific phandle
> > > >>                               to TV TCON output>;
> > > >>                       
> > > >>                       };
> > > >>               
> > > >>               };
> > > >>               
> > > >>               tcon_top_out: port@1 {
> > > >>               
> > > >>                       #address-cells = <1>;
> > > >>                       #size-cells = <0>;
> > > >>                       reg = <1>;
> > > >>                       
> > > >>                       tcon_top_out_tcon0: endpoint@0 {
> > > >>                       
> > > >>                               reg = <0>;
> > > >>                               // here is mixer0 output connection, part
> > > >>                               of board DTS
> > > >>                               remote-endpoint = <board specific phandle
> > > >>                               to TCON>;
> > > >>                       
> > > >>                       };
> > > >>                       
> > > >>                       tcon_top_out_tcon1: endpoint@1 {
> > > >>                       
> > > >>                               reg = <1>;
> > > >>                               // here is mixer1 output connection, part
> > > >>                               of board DTS
> > > >>                               remote-endpoint = <board specific phandle
> > > >>                               to TCON>;
> > > >>                       
> > > >>                       };
> > > >>                       
> > > >>                       tcon_top_out_hdmi: endpoint@2 {
> > > >>                       
> > > >>                               reg = <2>;
> > > >>                               remote-endpoint = <&hdmi_in_tcon_top>;
> > > >>                       
> > > >>                       };
> > > >>               
> > > >>               };
> > > >>       
> > > >>       };
> > > >> 
> > > >> };
> > > > 
> > > > IIRC, each port is supposed to be one route for the data, so we would
> > > > have multiple ports, one for the mixers in input and for the tcon in
> > > > output, and one for the TCON in input and for the HDMI/TV in
> > > > output. Rob might correct me here.
> 
> Ok, that seems more clean approach. I'll have to extend graph traversing 
> algorithm in sun4i_drv.c, but that's no problem.
> 
> Just to be clear, you have in mind 3 pairs of ports (0/1 for mixer0 mux, 2/3 
> for mixer1 and 4/5 for HDMI input), right? That way each mux is represented 
> with one pair of ports, even numbered for input and odd numbered for output.

Yep, unless Rob feels otherwise.

Maxime

Jernej Škrabec June 6, 2018, 10:30 p.m. UTC | #11

Dne ponedeljek, 04. junij 2018 ob 18:23:57 CEST je Maxime Ripard napisal(a):
> On Mon, Jun 04, 2018 at 05:09:56PM +0200, Jernej Škrabec wrote:
> > Dne ponedeljek, 04. junij 2018 ob 13:50:34 CEST je Maxime Ripard 
napisal(a):
> > > On Fri, Jun 01, 2018 at 09:19:43AM -0700, Chen-Yu Tsai wrote:
> > > > On Fri, Jun 1, 2018 at 8:29 AM, Maxime Ripard
> > > > <maxime.ripard@bootlin.com>
> > 
> > wrote:
> > > > > On Thu, May 31, 2018 at 07:54:08PM +0200, Jernej Škrabec wrote:
> > > > >> Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard 
napisal(a):
> > > > >> > On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
> > > > >> > > >> > > + if (tcon->quirks->needs_tcon_top) {
> > > > >> > > >> > > +         struct device_node *np;
> > > > >> > > >> > > +
> > > > >> > > >> > > +         np = of_parse_phandle(dev->of_node,
> > > > >> > > >> > > "allwinner,tcon-top",
> > > > >> > > >> > > 0);
> > > > >> > > >> > > +         if (np) {
> > > > >> > > >> > > +                 struct platform_device *pdev;
> > > > >> > > >> > > +
> > > > >> > > >> > > +                 pdev = of_find_device_by_node(np);
> > > > >> > > >> > > +                 if (pdev)
> > > > >> > > >> > > +                         tcon->tcon_top =
> > > > >> > > >> > > platform_get_drvdata(pdev);
> > > > >> > > >> > > +                 of_node_put(np);
> > > > >> > > >> > > +
> > > > >> > > >> > > +                 if (!tcon->tcon_top)
> > > > >> > > >> > > +                         return -EPROBE_DEFER;
> > > > >> > > >> > > +         }
> > > > >> > > >> > > + }
> > > > >> > > >> > > +
> > > > >> > > >> > 
> > > > >> > > >> > I might have missed it, but I've not seen the bindings
> > > > >> > > >> > additions for
> > > > >> > > >> > that property. This shouldn't really be done that way
> > > > >> > > >> > anyway,
> > > > >> > > >> > instead
> > > > >> > > >> > of using a direct phandle, you should be using the
> > > > >> > > >> > of-graph,
> > > > >> > > >> > with the
> > > > >> > > >> > TCON-top sitting where it belongs in the flow of data.
> > > > >> > > >> 
> > > > >> > > >> Just to answer to the first question, it did describe it in
> > > > >> > > >> "[PATCH
> > > > >> > > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI
> > > > >> > > >> pipeline".
> > > > >> > > >> 
> > > > >> > > >> As why I designed it that way - HW representation could be
> > > > >> > > >> described
> > > > >> > > >> that way> >>
> > > > >> > > >> 
> > > > >> > > >> (ASCII art makes sense when fixed width font is used to view
> > 
> > it):
> > > > >> > > >>                             / LCD0/LVDS0
> > > > >> > > >>                 
> > > > >> > > >>                 / TCON-LCD0
> > > > >> > > >>                 
> > > > >> > > >>                 |           \ MIPI DSI
> > > > >> > > >> 
> > > > >> > > >> mixer0          |
> > > > >> > > >> 
> > > > >> > > >>        \        / TCON-LCD1 - LCD1/LVDS1
> > > > >> > > >>        
> > > > >> > > >>         TCON-TOP
> > > > >> > > >>        
> > > > >> > > >>        /        \ TCON-TV0 - TVE0/RGB
> > > > >> > > >> 
> > > > >> > > >> mixer1          |          \
> > > > >> > > >> 
> > > > >> > > >>                 |           TCON-TOP - HDMI
> > > > >> > > >>                 |          
> > > > >> > > >>                 |          /
> > > > >> > > >>                 
> > > > >> > > >>                 \ TCON-TV1 - TVE1/RGB
> > > > >> > > >> 
> > > > >> > > >> This is a bit simplified, since there is also TVE-TOP, which
> > > > >> > > >> is
> > > > >> > > >> responsible
> > > > >> > > >> for sharing 4 DACs between both TVE encoders. You can have
> > > > >> > > >> two
> > > > >> > > >> TV outs
> > > > >> > > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice versa.
> > > > >> > > >> It
> > > > >> > > >> even
> > > > >> > > >> seems that you can arbitrarly choose which DAC is
> > > > >> > > >> responsible
> > > > >> > > >> for
> > > > >> > > >> which signal, so there is a ton of possible end
> > > > >> > > >> combinations,
> > > > >> > > >> but I'm
> > > > >> > > >> not 100% sure.
> > > > >> > > >> 
> > > > >> > > >> Even though I wrote TCON-TOP twice, this is same unit in HW.
> > > > >> > > >> R40
> > > > >> > > >> manual
> > > > >> > > >> suggest more possibilities, although some of them seem
> > > > >> > > >> wrong,
> > > > >> > > >> like RGB
> > > > >> > > >> feeding from LCD TCON. That is confirmed to be wrong when
> > > > >> > > >> checking BSP
> > > > >> > > >> code.
> > > > >> > > >> 
> > > > >> > > >> Additionally, TCON-TOP comes in the middle of TVE0 and LCD0,
> > > > >> > > >> TVE1 and
> > > > >> > > >> LCD1 for pin muxing, although I'm not sure why is that
> > > > >> > > >> needed at
> > > > >> > > >> all,
> > > > >> > > >> since according to R40 datasheet, TVE0 and TVE1 pins are
> > > > >> > > >> dedicated and
> > > > >> > > >> not on PORT D and PORT H, respectively, as TCON-TOP
> > > > >> > > >> documentation
> > > > >> > > >> suggest. However, HSYNC and PSYNC lines might be shared
> > > > >> > > >> between
> > > > >> > > >> TVE
> > > > >> > > >> (when it works in RGB mode) and LCD. But that is just my
> > > > >> > > >> guess
> > > > >> > > >> since
> > > > >> > > >> I'm not really familiar with RGB and LCD interfaces.
> > > > >> > > >> 
> > > > >> > > >> I'm really not sure what would be the best representation in
> > > > >> > > >> OF-graph.
> > > > >> > > >> Can you suggest one?
> > > > >> > > > 
> > > > >> > > > Rob might disagree on this one, but I don't see anything
> > > > >> > > > wrong
> > > > >> > > > with
> > > > >> > > > having loops in the graph. If the TCON-TOP can be both the
> > > > >> > > > input
> > > > >> > > > and
> > > > >> > > > output of the TCONs, then so be it, and have it described
> > > > >> > > > that
> > > > >> > > > way in
> > > > >> > > > the graph.
> > > > >> > > > 
> > > > >> > > > The code is already able to filter out nodes that have
> > > > >> > > > already
> > > > >> > > > been
> > > > >> > > > added to the list of devices we need to wait for in the
> > > > >> > > > component
> > > > >> > > > framework, so that should work as well.
> > > > >> > > > 
> > > > >> > > > And we'd need to describe TVE-TOP as well, even though we
> > > > >> > > > don't
> > > > >> > > > have a
> > > > >> > > > driver for it yet. That will simplify the backward
> > > > >> > > > compatibility
> > > > >> > > > later
> > > > >> > > > on.
> > > > >> > > 
> > > > >> > > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue
> > > > >> > > layer
> > > > >> > > that
> > > > >> > > binds everything together, and provides signal routing, kind of
> > > > >> > > like
> > > > >> > > DE-TOP on A64. So the signal mux controls that were originally
> > > > >> > > found
> > > > >> > > in TCON0 and TVE0 were moved out.
> > > > >> > > 
> > > > >> > > The driver needs to know about that, but the graph about
> > > > >> > > doesn't
> > > > >> > > make
> > > > >> > > much sense directly. Without looking at the manual, I
> > > > >> > > understand it
> > > > >> > > to
> > > > >> > > likely be one mux between the mixers and TCONs, and one between
> > > > >> > > the
> > > > >> > > TCON-TVs and HDMI. Would it make more sense to just have the
> > > > >> > > graph
> > > > >> > > connections between the muxed components, and remove TCON-TOP
> > > > >> > > from
> > > > >> > > it, like we had in the past? A phandle could be used to
> > > > >> > > reference
> > > > >> > > the TCON-TOP for mux controls, in addition to the clocks and
> > > > >> > > resets.
> > > > >> > > 
> > > > >> > > For TVE, we would need something to represent each of the
> > > > >> > > output
> > > > >> > > pins,
> > > > >> > > so the device tree can actually describe what kind of signal,
> > > > >> > > be it
> > > > >> > > each component of RGB/YUV or composite video, is wanted on each
> > > > >> > > pin,
> > > > >> > > if any. This is also needed on the A20 for the Cubietruck, so
> > > > >> > > we
> > > > >> > > can
> > > > >> > > describe which pins are tied to the VGA connector, and which
> > > > >> > > one
> > > > >> > > does
> > > > >> > > R, G, or B.
> > > > >> > 
> > > > >> > I guess we'll see how the DT maintainers feel about this, but my
> > > > >> > impression is that the OF graph should model the flow of data
> > > > >> > between
> > > > >> > the devices. If there's a mux somewhere, then the data is
> > > > >> > definitely
> > > > >> > going through it, and as such it should be part of the graph.
> > > > >> 
> > > > >> I concur, but I spent few days thinking how to represent this
> > > > >> sanely in
> > > > >> graph, but I didn't find any good solution. I'll represent here my
> > > > >> idea and please tell your opinion before I start implementing it.
> > > > >> 
> > > > >> First, let me be clear that mixer0 and mixer1 don't have same
> > > > >> capabilities
> > > > >> (different number of planes, mixer0 supports writeback, mixer1 does
> > > > >> not,
> > > > >> etc.). Thus, it does matter which mixer is connected to which
> > > > >> TCON/encoder.
> > > > >> mixer0 is meant to be connected to main display and mixer1 to
> > > > >> auxiliary. That obviously depends on end system.
> > > > >> 
> > > > >> So, TCON TOP has 3 muxes, which have to be represented in graph.
> > > > >> Two of
> > > > >> them are for mixer/TCON relationship (each of them 1 input and 4
> > > > >> possible outputs) and one for TV TCON/HDMI pair selection (2
> > > > >> possible
> > > > >> inputs, 1 output).
> > > > >> 
> > > > >> According to current practice in sun4i-drm driver, graph has to
> > > > >> have
> > > > >> port 0, representing input and port 1, representing output. This
> > > > >> would
> > > > >> mean that graph looks something like that:
> > > > >> 
> > > > >> tcon_top: tcon-top@1c70000 {
> > > > >> 
> > > > >>       compatible = "allwinner,sun8i-r40-tcon-top";
> > > > >>       ...
> > > > >>       ports {
> > > > >>       
> > > > >>               #address-cells = <1>;
> > > > >>               #size-cells = <0>;
> > > > >>               
> > > > >>               tcon_top_in: port@0 {
> > > > >>               
> > > > >>                       #address-cells = <1>;
> > > > >>                       #size-cells = <0>;
> > > > >>                       reg = <0>;
> > > > >>                       
> > > > >>                       tcon_top_in_mixer0: endpoint@0 {
> > > > >>                       
> > > > >>                               reg = <0>;
> > > > >>                               remote-endpoint =
> > > > >>                               <&mixer0_out_tcon_top>;
> > > > >>                       
> > > > >>                       };
> > > > >>                       
> > > > >>                       tcon_top_in_mixer1: endpoint@1 {
> > > > >>                       
> > > > >>                               reg = <1>;
> > > > >>                               remote-endpoint =
> > > > >>                               <&mixer1_out_tcon_top>;
> > > > >>                       
> > > > >>                       };
> > > > >>                       
> > > > >>                       tcon_top_in_tcon_tv: endpoint@2 {
> > > > >>                       
> > > > >>                               reg = <2>;
> > > > >>                               // here is HDMI input connection,
> > > > >>                               part of
> > > > >>                               board DTS
> > > > >>                               remote-endpoint = <board specific
> > > > >>                               phandle
> > > > >>                               to TV TCON output>;
> > > > >>                       
> > > > >>                       };
> > > > >>               
> > > > >>               };
> > > > >>               
> > > > >>               tcon_top_out: port@1 {
> > > > >>               
> > > > >>                       #address-cells = <1>;
> > > > >>                       #size-cells = <0>;
> > > > >>                       reg = <1>;
> > > > >>                       
> > > > >>                       tcon_top_out_tcon0: endpoint@0 {
> > > > >>                       
> > > > >>                               reg = <0>;
> > > > >>                               // here is mixer0 output connection,
> > > > >>                               part
> > > > >>                               of board DTS
> > > > >>                               remote-endpoint = <board specific
> > > > >>                               phandle
> > > > >>                               to TCON>;
> > > > >>                       
> > > > >>                       };
> > > > >>                       
> > > > >>                       tcon_top_out_tcon1: endpoint@1 {
> > > > >>                       
> > > > >>                               reg = <1>;
> > > > >>                               // here is mixer1 output connection,
> > > > >>                               part
> > > > >>                               of board DTS
> > > > >>                               remote-endpoint = <board specific
> > > > >>                               phandle
> > > > >>                               to TCON>;
> > > > >>                       
> > > > >>                       };
> > > > >>                       
> > > > >>                       tcon_top_out_hdmi: endpoint@2 {
> > > > >>                       
> > > > >>                               reg = <2>;
> > > > >>                               remote-endpoint =
> > > > >>                               <&hdmi_in_tcon_top>;
> > > > >>                       
> > > > >>                       };
> > > > >>               
> > > > >>               };
> > > > >>       
> > > > >>       };
> > > > >> 
> > > > >> };
> > > > > 
> > > > > IIRC, each port is supposed to be one route for the data, so we
> > > > > would
> > > > > have multiple ports, one for the mixers in input and for the tcon in
> > > > > output, and one for the TCON in input and for the HDMI/TV in
> > > > > output. Rob might correct me here.
> > 
> > Ok, that seems more clean approach. I'll have to extend graph traversing
> > algorithm in sun4i_drv.c, but that's no problem.
> > 
> > Just to be clear, you have in mind 3 pairs of ports (0/1 for mixer0 mux,
> > 2/3 for mixer1 and 4/5 for HDMI input), right? That way each mux is
> > represented with one pair of ports, even numbered for input and odd
> > numbered for output.
> Yep, unless Rob feels otherwise.

I found an issue with this concept.

HDMI driver (sun8i_dw_hdmi.c) uses drm_of_find_possible_crtcs() to find 
connected crtcs (TCONs) to HDMI. This function assumes that crtc and encoder 
are directly connected through of_graph, but that is not the case with TCON 
TOP HDMI mux anymore. 
I could give TCON TOP node as an input to this function, but that won't work, 
since TCON TOP can have connections to other crtcs, not only that of HDMI and 
they will also be picked up by drm_of_find_possible_crtcs().

Any suggestion how to solve this nicely? I think creating my own version of 
drm_of_find_possible_crtcs() which considers that case is one way, but not 
very nice solution. Alternatively, we can fix possible_crtcs to BIT(0), since 
it always has only one input. This is done in meson_dw_hdmi.c for example. 

Best regards,
Jernej

Jernej Škrabec June 8, 2018, 5:17 a.m. UTC | #12

Dne četrtek, 07. junij 2018 ob 00:30:24 CEST je Jernej Škrabec napisal(a):
> Dne ponedeljek, 04. junij 2018 ob 18:23:57 CEST je Maxime Ripard napisal(a):
> > On Mon, Jun 04, 2018 at 05:09:56PM +0200, Jernej Škrabec wrote:
> > > Dne ponedeljek, 04. junij 2018 ob 13:50:34 CEST je Maxime Ripard
> 
> napisal(a):
> > > > On Fri, Jun 01, 2018 at 09:19:43AM -0700, Chen-Yu Tsai wrote:
> > > > > On Fri, Jun 1, 2018 at 8:29 AM, Maxime Ripard
> > > > > <maxime.ripard@bootlin.com>
> > > 
> > > wrote:
> > > > > > On Thu, May 31, 2018 at 07:54:08PM +0200, Jernej Škrabec wrote:
> > > > > >> Dne četrtek, 31. maj 2018 ob 11:21:33 CEST je Maxime Ripard
> 
> napisal(a):
> > > > > >> > On Thu, May 24, 2018 at 03:01:09PM -0700, Chen-Yu Tsai wrote:
> > > > > >> > > >> > > + if (tcon->quirks->needs_tcon_top) {
> > > > > >> > > >> > > +         struct device_node *np;
> > > > > >> > > >> > > +
> > > > > >> > > >> > > +         np = of_parse_phandle(dev->of_node,
> > > > > >> > > >> > > "allwinner,tcon-top",
> > > > > >> > > >> > > 0);
> > > > > >> > > >> > > +         if (np) {
> > > > > >> > > >> > > +                 struct platform_device *pdev;
> > > > > >> > > >> > > +
> > > > > >> > > >> > > +                 pdev = of_find_device_by_node(np);
> > > > > >> > > >> > > +                 if (pdev)
> > > > > >> > > >> > > +                         tcon->tcon_top =
> > > > > >> > > >> > > platform_get_drvdata(pdev);
> > > > > >> > > >> > > +                 of_node_put(np);
> > > > > >> > > >> > > +
> > > > > >> > > >> > > +                 if (!tcon->tcon_top)
> > > > > >> > > >> > > +                         return -EPROBE_DEFER;
> > > > > >> > > >> > > +         }
> > > > > >> > > >> > > + }
> > > > > >> > > >> > > +
> > > > > >> > > >> > 
> > > > > >> > > >> > I might have missed it, but I've not seen the bindings
> > > > > >> > > >> > additions for
> > > > > >> > > >> > that property. This shouldn't really be done that way
> > > > > >> > > >> > anyway,
> > > > > >> > > >> > instead
> > > > > >> > > >> > of using a direct phandle, you should be using the
> > > > > >> > > >> > of-graph,
> > > > > >> > > >> > with the
> > > > > >> > > >> > TCON-top sitting where it belongs in the flow of data.
> > > > > >> > > >> 
> > > > > >> > > >> Just to answer to the first question, it did describe it
> > > > > >> > > >> in
> > > > > >> > > >> "[PATCH
> > > > > >> > > >> 07/15] dt- bindings: display: sun4i-drm: Add R40 HDMI
> > > > > >> > > >> pipeline".
> > > > > >> > > >> 
> > > > > >> > > >> As why I designed it that way - HW representation could be
> > > > > >> > > >> described
> > > > > >> > > >> that way> >>
> > > > > >> > > >> 
> > > > > >> > > >> (ASCII art makes sense when fixed width font is used to
> > > > > >> > > >> view
> > > 
> > > it):
> > > > > >> > > >>                             / LCD0/LVDS0
> > > > > >> > > >>                 
> > > > > >> > > >>                 / TCON-LCD0
> > > > > >> > > >>                 
> > > > > >> > > >>                 |           \ MIPI DSI
> > > > > >> > > >> 
> > > > > >> > > >> mixer0          |
> > > > > >> > > >> 
> > > > > >> > > >>        \        / TCON-LCD1 - LCD1/LVDS1
> > > > > >> > > >>        
> > > > > >> > > >>         TCON-TOP
> > > > > >> > > >>        
> > > > > >> > > >>        /        \ TCON-TV0 - TVE0/RGB
> > > > > >> > > >> 
> > > > > >> > > >> mixer1          |          \
> > > > > >> > > >> 
> > > > > >> > > >>                 |           TCON-TOP - HDMI
> > > > > >> > > >>                 |          
> > > > > >> > > >>                 |          /
> > > > > >> > > >>                 
> > > > > >> > > >>                 \ TCON-TV1 - TVE1/RGB
> > > > > >> > > >> 
> > > > > >> > > >> This is a bit simplified, since there is also TVE-TOP,
> > > > > >> > > >> which
> > > > > >> > > >> is
> > > > > >> > > >> responsible
> > > > > >> > > >> for sharing 4 DACs between both TVE encoders. You can have
> > > > > >> > > >> two
> > > > > >> > > >> TV outs
> > > > > >> > > >> (PAL/ NTSC) or TVE0 as TV out and TVE1 as RGB or vice
> > > > > >> > > >> versa.
> > > > > >> > > >> It
> > > > > >> > > >> even
> > > > > >> > > >> seems that you can arbitrarly choose which DAC is
> > > > > >> > > >> responsible
> > > > > >> > > >> for
> > > > > >> > > >> which signal, so there is a ton of possible end
> > > > > >> > > >> combinations,
> > > > > >> > > >> but I'm
> > > > > >> > > >> not 100% sure.
> > > > > >> > > >> 
> > > > > >> > > >> Even though I wrote TCON-TOP twice, this is same unit in
> > > > > >> > > >> HW.
> > > > > >> > > >> R40
> > > > > >> > > >> manual
> > > > > >> > > >> suggest more possibilities, although some of them seem
> > > > > >> > > >> wrong,
> > > > > >> > > >> like RGB
> > > > > >> > > >> feeding from LCD TCON. That is confirmed to be wrong when
> > > > > >> > > >> checking BSP
> > > > > >> > > >> code.
> > > > > >> > > >> 
> > > > > >> > > >> Additionally, TCON-TOP comes in the middle of TVE0 and
> > > > > >> > > >> LCD0,
> > > > > >> > > >> TVE1 and
> > > > > >> > > >> LCD1 for pin muxing, although I'm not sure why is that
> > > > > >> > > >> needed at
> > > > > >> > > >> all,
> > > > > >> > > >> since according to R40 datasheet, TVE0 and TVE1 pins are
> > > > > >> > > >> dedicated and
> > > > > >> > > >> not on PORT D and PORT H, respectively, as TCON-TOP
> > > > > >> > > >> documentation
> > > > > >> > > >> suggest. However, HSYNC and PSYNC lines might be shared
> > > > > >> > > >> between
> > > > > >> > > >> TVE
> > > > > >> > > >> (when it works in RGB mode) and LCD. But that is just my
> > > > > >> > > >> guess
> > > > > >> > > >> since
> > > > > >> > > >> I'm not really familiar with RGB and LCD interfaces.
> > > > > >> > > >> 
> > > > > >> > > >> I'm really not sure what would be the best representation
> > > > > >> > > >> in
> > > > > >> > > >> OF-graph.
> > > > > >> > > >> Can you suggest one?
> > > > > >> > > > 
> > > > > >> > > > Rob might disagree on this one, but I don't see anything
> > > > > >> > > > wrong
> > > > > >> > > > with
> > > > > >> > > > having loops in the graph. If the TCON-TOP can be both the
> > > > > >> > > > input
> > > > > >> > > > and
> > > > > >> > > > output of the TCONs, then so be it, and have it described
> > > > > >> > > > that
> > > > > >> > > > way in
> > > > > >> > > > the graph.
> > > > > >> > > > 
> > > > > >> > > > The code is already able to filter out nodes that have
> > > > > >> > > > already
> > > > > >> > > > been
> > > > > >> > > > added to the list of devices we need to wait for in the
> > > > > >> > > > component
> > > > > >> > > > framework, so that should work as well.
> > > > > >> > > > 
> > > > > >> > > > And we'd need to describe TVE-TOP as well, even though we
> > > > > >> > > > don't
> > > > > >> > > > have a
> > > > > >> > > > driver for it yet. That will simplify the backward
> > > > > >> > > > compatibility
> > > > > >> > > > later
> > > > > >> > > > on.
> > > > > >> > > 
> > > > > >> > > I'm getting the feeling that TCON-TOP / TVE-TOP is the glue
> > > > > >> > > layer
> > > > > >> > > that
> > > > > >> > > binds everything together, and provides signal routing, kind
> > > > > >> > > of
> > > > > >> > > like
> > > > > >> > > DE-TOP on A64. So the signal mux controls that were
> > > > > >> > > originally
> > > > > >> > > found
> > > > > >> > > in TCON0 and TVE0 were moved out.
> > > > > >> > > 
> > > > > >> > > The driver needs to know about that, but the graph about
> > > > > >> > > doesn't
> > > > > >> > > make
> > > > > >> > > much sense directly. Without looking at the manual, I
> > > > > >> > > understand it
> > > > > >> > > to
> > > > > >> > > likely be one mux between the mixers and TCONs, and one
> > > > > >> > > between
> > > > > >> > > the
> > > > > >> > > TCON-TVs and HDMI. Would it make more sense to just have the
> > > > > >> > > graph
> > > > > >> > > connections between the muxed components, and remove TCON-TOP
> > > > > >> > > from
> > > > > >> > > it, like we had in the past? A phandle could be used to
> > > > > >> > > reference
> > > > > >> > > the TCON-TOP for mux controls, in addition to the clocks and
> > > > > >> > > resets.
> > > > > >> > > 
> > > > > >> > > For TVE, we would need something to represent each of the
> > > > > >> > > output
> > > > > >> > > pins,
> > > > > >> > > so the device tree can actually describe what kind of signal,
> > > > > >> > > be it
> > > > > >> > > each component of RGB/YUV or composite video, is wanted on
> > > > > >> > > each
> > > > > >> > > pin,
> > > > > >> > > if any. This is also needed on the A20 for the Cubietruck, so
> > > > > >> > > we
> > > > > >> > > can
> > > > > >> > > describe which pins are tied to the VGA connector, and which
> > > > > >> > > one
> > > > > >> > > does
> > > > > >> > > R, G, or B.
> > > > > >> > 
> > > > > >> > I guess we'll see how the DT maintainers feel about this, but
> > > > > >> > my
> > > > > >> > impression is that the OF graph should model the flow of data
> > > > > >> > between
> > > > > >> > the devices. If there's a mux somewhere, then the data is
> > > > > >> > definitely
> > > > > >> > going through it, and as such it should be part of the graph.
> > > > > >> 
> > > > > >> I concur, but I spent few days thinking how to represent this
> > > > > >> sanely in
> > > > > >> graph, but I didn't find any good solution. I'll represent here
> > > > > >> my
> > > > > >> idea and please tell your opinion before I start implementing it.
> > > > > >> 
> > > > > >> First, let me be clear that mixer0 and mixer1 don't have same
> > > > > >> capabilities
> > > > > >> (different number of planes, mixer0 supports writeback, mixer1
> > > > > >> does
> > > > > >> not,
> > > > > >> etc.). Thus, it does matter which mixer is connected to which
> > > > > >> TCON/encoder.
> > > > > >> mixer0 is meant to be connected to main display and mixer1 to
> > > > > >> auxiliary. That obviously depends on end system.
> > > > > >> 
> > > > > >> So, TCON TOP has 3 muxes, which have to be represented in graph.
> > > > > >> Two of
> > > > > >> them are for mixer/TCON relationship (each of them 1 input and 4
> > > > > >> possible outputs) and one for TV TCON/HDMI pair selection (2
> > > > > >> possible
> > > > > >> inputs, 1 output).
> > > > > >> 
> > > > > >> According to current practice in sun4i-drm driver, graph has to
> > > > > >> have
> > > > > >> port 0, representing input and port 1, representing output. This
> > > > > >> would
> > > > > >> mean that graph looks something like that:
> > > > > >> 
> > > > > >> tcon_top: tcon-top@1c70000 {
> > > > > >> 
> > > > > >>       compatible = "allwinner,sun8i-r40-tcon-top";
> > > > > >>       ...
> > > > > >>       ports {
> > > > > >>       
> > > > > >>               #address-cells = <1>;
> > > > > >>               #size-cells = <0>;
> > > > > >>               
> > > > > >>               tcon_top_in: port@0 {
> > > > > >>               
> > > > > >>                       #address-cells = <1>;
> > > > > >>                       #size-cells = <0>;
> > > > > >>                       reg = <0>;
> > > > > >>                       
> > > > > >>                       tcon_top_in_mixer0: endpoint@0 {
> > > > > >>                       
> > > > > >>                               reg = <0>;
> > > > > >>                               remote-endpoint =
> > > > > >>                               <&mixer0_out_tcon_top>;
> > > > > >>                       
> > > > > >>                       };
> > > > > >>                       
> > > > > >>                       tcon_top_in_mixer1: endpoint@1 {
> > > > > >>                       
> > > > > >>                               reg = <1>;
> > > > > >>                               remote-endpoint =
> > > > > >>                               <&mixer1_out_tcon_top>;
> > > > > >>                       
> > > > > >>                       };
> > > > > >>                       
> > > > > >>                       tcon_top_in_tcon_tv: endpoint@2 {
> > > > > >>                       
> > > > > >>                               reg = <2>;
> > > > > >>                               // here is HDMI input connection,
> > > > > >>                               part of
> > > > > >>                               board DTS
> > > > > >>                               remote-endpoint = <board specific
> > > > > >>                               phandle
> > > > > >>                               to TV TCON output>;
> > > > > >>                       
> > > > > >>                       };
> > > > > >>               
> > > > > >>               };
> > > > > >>               
> > > > > >>               tcon_top_out: port@1 {
> > > > > >>               
> > > > > >>                       #address-cells = <1>;
> > > > > >>                       #size-cells = <0>;
> > > > > >>                       reg = <1>;
> > > > > >>                       
> > > > > >>                       tcon_top_out_tcon0: endpoint@0 {
> > > > > >>                       
> > > > > >>                               reg = <0>;
> > > > > >>                               // here is mixer0 output
> > > > > >>                               connection,
> > > > > >>                               part
> > > > > >>                               of board DTS
> > > > > >>                               remote-endpoint = <board specific
> > > > > >>                               phandle
> > > > > >>                               to TCON>;
> > > > > >>                       
> > > > > >>                       };
> > > > > >>                       
> > > > > >>                       tcon_top_out_tcon1: endpoint@1 {
> > > > > >>                       
> > > > > >>                               reg = <1>;
> > > > > >>                               // here is mixer1 output
> > > > > >>                               connection,
> > > > > >>                               part
> > > > > >>                               of board DTS
> > > > > >>                               remote-endpoint = <board specific
> > > > > >>                               phandle
> > > > > >>                               to TCON>;
> > > > > >>                       
> > > > > >>                       };
> > > > > >>                       
> > > > > >>                       tcon_top_out_hdmi: endpoint@2 {
> > > > > >>                       
> > > > > >>                               reg = <2>;
> > > > > >>                               remote-endpoint =
> > > > > >>                               <&hdmi_in_tcon_top>;
> > > > > >>                       
> > > > > >>                       };
> > > > > >>               
> > > > > >>               };
> > > > > >>       
> > > > > >>       };
> > > > > >> 
> > > > > >> };
> > > > > > 
> > > > > > IIRC, each port is supposed to be one route for the data, so we
> > > > > > would
> > > > > > have multiple ports, one for the mixers in input and for the tcon
> > > > > > in
> > > > > > output, and one for the TCON in input and for the HDMI/TV in
> > > > > > output. Rob might correct me here.
> > > 
> > > Ok, that seems more clean approach. I'll have to extend graph traversing
> > > algorithm in sun4i_drv.c, but that's no problem.
> > > 
> > > Just to be clear, you have in mind 3 pairs of ports (0/1 for mixer0 mux,
> > > 2/3 for mixer1 and 4/5 for HDMI input), right? That way each mux is
> > > represented with one pair of ports, even numbered for input and odd
> > > numbered for output.
> > 
> > Yep, unless Rob feels otherwise.
> 
> I found an issue with this concept.
> 
> HDMI driver (sun8i_dw_hdmi.c) uses drm_of_find_possible_crtcs() to find
> connected crtcs (TCONs) to HDMI. This function assumes that crtc and encoder
> are directly connected through of_graph, but that is not the case with TCON
> TOP HDMI mux anymore.
> I could give TCON TOP node as an input to this function, but that won't
> work, since TCON TOP can have connections to other crtcs, not only that of
> HDMI and they will also be picked up by drm_of_find_possible_crtcs().
> 
> Any suggestion how to solve this nicely? I think creating my own version of
> drm_of_find_possible_crtcs() which considers that case is one way, but not
> very nice solution. Alternatively, we can fix possible_crtcs to BIT(0),

This doesn't seem like a good solution, since it doesn't work in dual head 
system. I'll take first approach.

Best regards,
Jernej

> since it always has only one input. This is done in meson_dw_hdmi.c for
> example.

[06/15] drm/sun4i: tcon: Add support for tcon-top

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