| Message ID | 20190120172534.24617-5-lkundrak@v3.sk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Bindings for Armada display subsystem | expand |
On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > The Marvell Armada DRM master device is a virtual device needed to list all > nodes that comprise the graphics subsystem. > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > --- > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > index de4cca9432c8..3dbfa8047f0b 100644 > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > @@ -1,3 +1,27 @@ > +Marvell Armada DRM master device > +================================ > + > +The Marvell Armada DRM master device is a virtual device needed to list all > +nodes that comprise the graphics subsystem. > + > +Required properties: > + > + - compatible: value should be "marvell,dove-display-subsystem", > + "marvell,armada-display-subsystem" > + - ports: a list of phandles pointing to display interface ports of CRTC > + devices > + - memory-region: phandle to a node describing memory to be used for the > + framebuffer > + > +Example: > + > + display-subsystem { > + compatible = "marvell,dove-display-subsystem", > + "marvell,armada-display-subsystem"; > + memory-region = <&display_reserved>; > + ports = <&lcd0_port>; If there is only one device, you don't need this virtual node. > + }; > + > Marvell Armada LCD controller > ============================= > > -- > 2.20.1 >
On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > The Marvell Armada DRM master device is a virtual device needed to list all > > nodes that comprise the graphics subsystem. > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > --- > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > 1 file changed, 24 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > index de4cca9432c8..3dbfa8047f0b 100644 > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > @@ -1,3 +1,27 @@ > > +Marvell Armada DRM master device > > +================================ > > + > > +The Marvell Armada DRM master device is a virtual device needed to list all > > +nodes that comprise the graphics subsystem. > > + > > +Required properties: > > + > > + - compatible: value should be "marvell,dove-display-subsystem", > > + "marvell,armada-display-subsystem" > > + - ports: a list of phandles pointing to display interface ports of CRTC > > + devices > > + - memory-region: phandle to a node describing memory to be used for the > > + framebuffer > > + > > +Example: > > + > > + display-subsystem { > > + compatible = "marvell,dove-display-subsystem", > > + "marvell,armada-display-subsystem"; > > + memory-region = <&display_reserved>; > > + ports = <&lcd0_port>; > > If there is only one device, you don't need this virtual node. By "one device" you mean one LCD controller (CRTC)? I suppose in the (single CRTC) example case, the display-subsystem node used to associate it with the memory region reserved for allocating the frame buffers from. Could that be done differently? Also, if the node is indeed made optional, then it's going to complicate things on the DRM side. Currently the driver that binds to the node creates the DRM device once it sees all the components connected to the ports appear. If we loose it, then the LCD controller driver would somehow need to find out that it's alone and create the DRM device itself. Thank you Lubo > > > > + }; > > + > > Marvell Armada LCD controller > > ============================= > > > > -- > > 2.20.1 > >
On Mon, Jan 21, 2019 at 9:46 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > nodes that comprise the graphics subsystem. > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > --- > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > 1 file changed, 24 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > @@ -1,3 +1,27 @@ > > > +Marvell Armada DRM master device > > > +================================ > > > + > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > +nodes that comprise the graphics subsystem. > > > + > > > +Required properties: > > > + > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > + "marvell,armada-display-subsystem" > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > + devices > > > + - memory-region: phandle to a node describing memory to be used for the > > > + framebuffer > > > + > > > +Example: > > > + > > > + display-subsystem { > > > + compatible = "marvell,dove-display-subsystem", > > > + "marvell,armada-display-subsystem"; > > > + memory-region = <&display_reserved>; > > > + ports = <&lcd0_port>; > > > > If there is only one device, you don't need this virtual node. > > By "one device" you mean one LCD controller (CRTC)? Yes. > I suppose in the (single CRTC) example case, the display-subsystem node > used to associate it with the memory region reserved for allocating the > frame buffers from. Could that be done differently? Move memory-region to the LCD controller node. > Also, if the node is indeed made optional, then it's going to > complicate things on the DRM side. Currently the driver that binds to > the node creates the DRM device once it sees all the components > connected to the ports appear. If we loose it, then the LCD controller > driver would somehow need to find out that it's alone and create the > DRM device itself. DT is not the only way to create devices. The DRM driver can bind to the LCDC node and then create a child CRTC device (or even multiple ones for h/w with multiple pipelines). You'll also notice that there are only 3 cases of this virtual node in the tree: STi, i.MX IPU, and Rockchip. That's because we've deprecated doing these virtual nodes for some time now. IOW, there are several examples of how to do this without a virtual node. Rob
On Mon, Jan 21, 2019 at 10:07:11AM -0600, Rob Herring wrote: > On Mon, Jan 21, 2019 at 9:46 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > > nodes that comprise the graphics subsystem. > > > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > > --- > > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > > 1 file changed, 24 insertions(+) > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > @@ -1,3 +1,27 @@ > > > > +Marvell Armada DRM master device > > > > +================================ > > > > + > > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > > +nodes that comprise the graphics subsystem. > > > > + > > > > +Required properties: > > > > + > > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > > + "marvell,armada-display-subsystem" > > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > > + devices > > > > + - memory-region: phandle to a node describing memory to be used for the > > > > + framebuffer > > > > + > > > > +Example: > > > > + > > > > + display-subsystem { > > > > + compatible = "marvell,dove-display-subsystem", > > > > + "marvell,armada-display-subsystem"; > > > > + memory-region = <&display_reserved>; > > > > + ports = <&lcd0_port>; > > > > > > If there is only one device, you don't need this virtual node. > > > > By "one device" you mean one LCD controller (CRTC)? > > Yes. How does that work (as far as the Linux implementation) ? I can't see a way that could work, while allowing the flexibility that Armada DRM allows (two completely independent LCD controllers as two separate DRM devices vs one DRM device containing both LCD controllers.) > > I suppose in the (single CRTC) example case, the display-subsystem node > > used to associate it with the memory region reserved for allocating the > > frame buffers from. Could that be done differently? > > Move memory-region to the LCD controller node. That doesn't work - it would appear in the wrong part of the driver. > > Also, if the node is indeed made optional, then it's going to > > complicate things on the DRM side. Currently the driver that binds to > > the node creates the DRM device once it sees all the components > > connected to the ports appear. If we loose it, then the LCD controller > > driver would somehow need to find out that it's alone and create the > > DRM device itself. > > DT is not the only way to create devices. The DRM driver can bind to > the LCDC node and then create a child CRTC device (or even multiple > ones for h/w with multiple pipelines). That seems completely upside down and rediculous to me - are you really suggesting that we should have some kind of virtual device in DT, and omit the _real_ physical devices for that, having the driver create the device with all the appropriate SoC resources? > You'll also notice that there are only 3 cases of this virtual node in > the tree: STi, i.MX IPU, and Rockchip. That's because we've deprecated > doing these virtual nodes for some time now. IOW, there are several > examples of how to do this without a virtual node. This driver has been in-tree with this setup for some time, although the documentation has been missing (we actually have a _lot_ of instances of that.) However, we have no in-tree DT using it. I don't really see how to satisfy your comments without totally restructuring the driver, which is going to be quite a big chunk of work. I'm not sure I have the motivation to do that right now.
On Mon, 2019-01-21 at 17:53 +0000, Russell King - ARM Linux admin wrote: > On Mon, Jan 21, 2019 at 10:07:11AM -0600, Rob Herring wrote: > > On Mon, Jan 21, 2019 at 9:46 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > > > nodes that comprise the graphics subsystem. > > > > > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > > > --- > > > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > > > 1 file changed, 24 insertions(+) > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > @@ -1,3 +1,27 @@ > > > > > +Marvell Armada DRM master device > > > > > +================================ > > > > > + > > > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > > > +nodes that comprise the graphics subsystem. > > > > > + > > > > > +Required properties: > > > > > + > > > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > > > + "marvell,armada-display-subsystem" > > > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > > > + devices > > > > > + - memory-region: phandle to a node describing memory to be used for the > > > > > + framebuffer > > > > > + > > > > > +Example: > > > > > + > > > > > + display-subsystem { > > > > > + compatible = "marvell,dove-display-subsystem", > > > > > + "marvell,armada-display-subsystem"; > > > > > + memory-region = <&display_reserved>; > > > > > + ports = <&lcd0_port>; > > > > > > > > If there is only one device, you don't need this virtual node. > > > > > > By "one device" you mean one LCD controller (CRTC)? > > > > Yes. > > How does that work (as far as the Linux implementation) ? I can't see > a way that could work, while allowing the flexibility that Armada DRM > allows (two completely independent LCD controllers as two separate DRM > devices vs one DRM device containing both LCD controllers.) > > > > I suppose in the (single CRTC) example case, the display-subsystem node > > > used to associate it with the memory region reserved for allocating the > > > frame buffers from. Could that be done differently? > > > > Move memory-region to the LCD controller node. > > That doesn't work - it would appear in the wrong part of the driver. > > > > Also, if the node is indeed made optional, then it's going to > > > complicate things on the DRM side. Currently the driver that binds to > > > the node creates the DRM device once it sees all the components > > > connected to the ports appear. If we loose it, then the LCD controller > > > driver would somehow need to find out that it's alone and create the > > > DRM device itself. > > > > DT is not the only way to create devices. The DRM driver can bind to > > the LCDC node and then create a child CRTC device (or even multiple > > ones for h/w with multiple pipelines). > > That seems completely upside down and rediculous to me - are you > really suggesting that we should have some kind of virtual device > in DT, and omit the _real_ physical devices for that, having the > driver create the device with all the appropriate SoC resources? Hmm, that's not how I read that. My understanding (putting aside practicality of the solution) is that Rob was merely suggesting that for the single LCDC case there would be just a single LCDC node in DT and the driver that binds to it would create the DRM device & CRTC device pair. > > You'll also notice that there are only 3 cases of this virtual node in > > the tree: STi, i.MX IPU, and Rockchip. That's because we've deprecated > > doing these virtual nodes for some time now. IOW, there are several > > examples of how to do this without a virtual node. > > This driver has been in-tree with this setup for some time, although > the documentation has been missing (we actually have a _lot_ of > instances of that.) However, we have no in-tree DT using it. > > I don't really see how to satisfy your comments without totally > restructuring the driver, which is going to be quite a big chunk > of work. I'm not sure I have the motivation to do that right now. Note that the initial objection was against the display-subsystem node being mandatory if "there is only one [LCDC] device". My understanding is that need to include the display-subsystem node for the multiple LCDC setup (on Dove platform) anyways. Is that correct? Rob, I'm wondering if there would be a possibility of finding some middle groud? Perhaps documenting, that the display-subsystem node would ideally be optional for single LCDC setups, but indicating that the Armada DRM driver actually requires is? Note that this is not a new driver -- it has been around since 2013, though, without useful DT bindings. Maybe it would do just well in company of the other three drivers you mentioned that use similar bindings. (Also, there seem to have substantial discussion regarding the bindings design back in '13, shedding some light into why the display-subsystem node was deemed useful: [1]) [1] https://www.mail-archive.com/dri-devel@lists.freedesktop.org/msg40358.html Thanks, Lubo
On Mon, Jan 21, 2019 at 09:45:22PM +0100, Lubomir Rintel wrote: > On Mon, 2019-01-21 at 17:53 +0000, Russell King - ARM Linux admin > wrote: > > On Mon, Jan 21, 2019 at 10:07:11AM -0600, Rob Herring wrote: > > > On Mon, Jan 21, 2019 at 9:46 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > > > > nodes that comprise the graphics subsystem. > > > > > > > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > > > > --- > > > > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > > > > 1 file changed, 24 insertions(+) > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > @@ -1,3 +1,27 @@ > > > > > > +Marvell Armada DRM master device > > > > > > +================================ > > > > > > + > > > > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > > > > +nodes that comprise the graphics subsystem. > > > > > > + > > > > > > +Required properties: > > > > > > + > > > > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > > > > + "marvell,armada-display-subsystem" > > > > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > > > > + devices > > > > > > + - memory-region: phandle to a node describing memory to be used for the > > > > > > + framebuffer > > > > > > + > > > > > > +Example: > > > > > > + > > > > > > + display-subsystem { > > > > > > + compatible = "marvell,dove-display-subsystem", > > > > > > + "marvell,armada-display-subsystem"; > > > > > > + memory-region = <&display_reserved>; > > > > > > + ports = <&lcd0_port>; > > > > > > > > > > If there is only one device, you don't need this virtual node. > > > > > > > > By "one device" you mean one LCD controller (CRTC)? > > > > > > Yes. > > > > How does that work (as far as the Linux implementation) ? I can't see > > a way that could work, while allowing the flexibility that Armada DRM > > allows (two completely independent LCD controllers as two separate DRM > > devices vs one DRM device containing both LCD controllers.) > > > > > > I suppose in the (single CRTC) example case, the display-subsystem node > > > > used to associate it with the memory region reserved for allocating the > > > > frame buffers from. Could that be done differently? > > > > > > Move memory-region to the LCD controller node. > > > > That doesn't work - it would appear in the wrong part of the driver. > > > > > > Also, if the node is indeed made optional, then it's going to > > > > complicate things on the DRM side. Currently the driver that binds to > > > > the node creates the DRM device once it sees all the components > > > > connected to the ports appear. If we loose it, then the LCD controller > > > > driver would somehow need to find out that it's alone and create the > > > > DRM device itself. > > > > > > DT is not the only way to create devices. The DRM driver can bind to > > > the LCDC node and then create a child CRTC device (or even multiple > > > ones for h/w with multiple pipelines). > > > > That seems completely upside down and rediculous to me - are you > > really suggesting that we should have some kind of virtual device > > in DT, and omit the _real_ physical devices for that, having the > > driver create the device with all the appropriate SoC resources? > > Hmm, that's not how I read that. My understanding (putting aside > practicality of the solution) is that Rob was merely suggesting that > for the single LCDC case there would be just a single LCDC node in DT > and the driver that binds to it would create the DRM device & CRTC > device pair. How would we know that was the case when the driver binds to the CRTC node? There is no back-link from the CRTC to the display-subsystem when there's a display-subsystem node present, so there's no way for the CRTC driver to know whether it should create the DRM device or not. I just can't see how this works at a technical level. > > > You'll also notice that there are only 3 cases of this virtual node in > > > the tree: STi, i.MX IPU, and Rockchip. That's because we've deprecated > > > doing these virtual nodes for some time now. IOW, there are several > > > examples of how to do this without a virtual node. > > > > This driver has been in-tree with this setup for some time, although > > the documentation has been missing (we actually have a _lot_ of > > instances of that.) However, we have no in-tree DT using it. > > > > I don't really see how to satisfy your comments without totally > > restructuring the driver, which is going to be quite a big chunk > > of work. I'm not sure I have the motivation to do that right now. > > Note that the initial objection was against the display-subsystem node > being mandatory if "there is only one [LCDC] device". > > My understanding is that need to include the display-subsystem node for > the multiple LCDC setup (on Dove platform) anyways. Is that correct? > > Rob, I'm wondering if there would be a possibility of finding some > middle groud? Perhaps documenting, that the display-subsystem node > would ideally be optional for single LCDC setups, but indicating that > the Armada DRM driver actually requires is? > > Note that this is not a new driver -- it has been around since 2013, > though, without useful DT bindings. Maybe it would do just well in > company of the other three drivers you mentioned that use similar > bindings. > > (Also, there seem to have substantial discussion regarding the bindings > design back in '13, shedding some light into why the display-subsystem > node was deemed useful: [1]) > > [1] https://www.mail-archive.com/dri-devel@lists.freedesktop.org/msg40358.html > > Thanks, > Lubo > >
On Mon, Jan 21, 2019 at 11:53 AM Russell King - ARM Linux admin <linux@armlinux.org.uk> wrote: > > On Mon, Jan 21, 2019 at 10:07:11AM -0600, Rob Herring wrote: > > On Mon, Jan 21, 2019 at 9:46 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > > > nodes that comprise the graphics subsystem. > > > > > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > > > --- > > > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > > > 1 file changed, 24 insertions(+) > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > @@ -1,3 +1,27 @@ > > > > > +Marvell Armada DRM master device > > > > > +================================ > > > > > + > > > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > > > +nodes that comprise the graphics subsystem. > > > > > + > > > > > +Required properties: > > > > > + > > > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > > > + "marvell,armada-display-subsystem" > > > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > > > + devices > > > > > + - memory-region: phandle to a node describing memory to be used for the > > > > > + framebuffer > > > > > + > > > > > +Example: > > > > > + > > > > > + display-subsystem { > > > > > + compatible = "marvell,dove-display-subsystem", > > > > > + "marvell,armada-display-subsystem"; > > > > > + memory-region = <&display_reserved>; > > > > > + ports = <&lcd0_port>; > > > > > > > > If there is only one device, you don't need this virtual node. > > > > > > By "one device" you mean one LCD controller (CRTC)? > > > > Yes. > > How does that work (as far as the Linux implementation) ? I can't see > a way that could work, while allowing the flexibility that Armada DRM > allows (two completely independent LCD controllers as two separate DRM > devices vs one DRM device containing both LCD controllers.) > > > > I suppose in the (single CRTC) example case, the display-subsystem node > > > used to associate it with the memory region reserved for allocating the > > > frame buffers from. Could that be done differently? > > > > Move memory-region to the LCD controller node. > > That doesn't work - it would appear in the wrong part of the driver. Why? You can fetch properties from other nodes. If you have 2 CRTCs, do you have 1 or 2 reserved memory regions? I'd think 2 with each one in the corresponding LCDC that uses them would be more flexible. Or just get the data out of the /reserved-memory node directly. Surely it has a compatible that you can find it with. > > > Also, if the node is indeed made optional, then it's going to > > > complicate things on the DRM side. Currently the driver that binds to > > > the node creates the DRM device once it sees all the components > > > connected to the ports appear. If we loose it, then the LCD controller > > > driver would somehow need to find out that it's alone and create the > > > DRM device itself. > > > > DT is not the only way to create devices. The DRM driver can bind to > > the LCDC node and then create a child CRTC device (or even multiple > > ones for h/w with multiple pipelines). > > That seems completely upside down and rediculous to me - are you > really suggesting that we should have some kind of virtual device > in DT, and omit the _real_ physical devices for that, having the > driver create the device with all the appropriate SoC resources? We create child platform devices that inherit from the parent in DT all the time. MFD child drivers are a common case. Sometime the child devices have DT nodes and sometimes they don't. Otherwise, do it the other way around. Create a virtual DRM device conditioned on the SoC: if (of_machine_is_compatible("foo,bar")) platform_device_register_simple(...) > > > You'll also notice that there are only 3 cases of this virtual node in > > the tree: STi, i.MX IPU, and Rockchip. That's because we've deprecated > > doing these virtual nodes for some time now. IOW, there are several > > examples of how to do this without a virtual node. > > This driver has been in-tree with this setup for some time, although > the documentation has been missing (we actually have a _lot_ of > instances of that.) However, we have no in-tree DT using it. The current Armada DRM driver has no binding to DT at all, so no, it is not just missing documentation or a dts file. > I don't really see how to satisfy your comments without totally > restructuring the driver, which is going to be quite a big chunk > of work. I'm not sure I have the motivation to do that right now. It's not a big chunk of work. Look at commit 246774d17fc0 ("drm/etnaviv: remove the need for a gpu-subsystem DT node") for an example. Rob
On Mon, Jan 21, 2019 at 05:58:50PM -0600, Rob Herring wrote: > On Mon, Jan 21, 2019 at 11:53 AM Russell King - ARM Linux admin > <linux@armlinux.org.uk> wrote: > > > > On Mon, Jan 21, 2019 at 10:07:11AM -0600, Rob Herring wrote: > > > On Mon, Jan 21, 2019 at 9:46 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > > > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > > > > nodes that comprise the graphics subsystem. > > > > > > > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > > > > --- > > > > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > > > > 1 file changed, 24 insertions(+) > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > @@ -1,3 +1,27 @@ > > > > > > +Marvell Armada DRM master device > > > > > > +================================ > > > > > > + > > > > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > > > > +nodes that comprise the graphics subsystem. > > > > > > + > > > > > > +Required properties: > > > > > > + > > > > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > > > > + "marvell,armada-display-subsystem" > > > > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > > > > + devices > > > > > > + - memory-region: phandle to a node describing memory to be used for the > > > > > > + framebuffer > > > > > > + > > > > > > +Example: > > > > > > + > > > > > > + display-subsystem { > > > > > > + compatible = "marvell,dove-display-subsystem", > > > > > > + "marvell,armada-display-subsystem"; > > > > > > + memory-region = <&display_reserved>; > > > > > > + ports = <&lcd0_port>; > > > > > > > > > > If there is only one device, you don't need this virtual node. > > > > > > > > By "one device" you mean one LCD controller (CRTC)? > > > > > > Yes. > > > > How does that work (as far as the Linux implementation) ? I can't see > > a way that could work, while allowing the flexibility that Armada DRM > > allows (two completely independent LCD controllers as two separate DRM > > devices vs one DRM device containing both LCD controllers.) > > > > > > I suppose in the (single CRTC) example case, the display-subsystem node > > > > used to associate it with the memory region reserved for allocating the > > > > frame buffers from. Could that be done differently? > > > > > > Move memory-region to the LCD controller node. > > > > That doesn't work - it would appear in the wrong part of the driver. > > Why? You can fetch properties from other nodes. > > If you have 2 CRTCs, do you have 1 or 2 reserved memory regions? I'd > think 2 with each one in the corresponding LCDC that uses them would > be more flexible. There would still be one reserved memory region, since it is shared between both LCDCs. > Or just get the data out of the /reserved-memory node directly. Surely > it has a compatible that you can find it with. I see that the DT reserved memory support has progressed since I wrote the armada code to deal with it, and it's now possible to make use of reserved memory via of_reserved_mem_lookup() rather than using the RESERVEDMEM_OF_DECLARE() and so forth. > > > > Also, if the node is indeed made optional, then it's going to > > > > complicate things on the DRM side. Currently the driver that binds to > > > > the node creates the DRM device once it sees all the components > > > > connected to the ports appear. If we loose it, then the LCD controller > > > > driver would somehow need to find out that it's alone and create the > > > > DRM device itself. > > > > > > DT is not the only way to create devices. The DRM driver can bind to > > > the LCDC node and then create a child CRTC device (or even multiple > > > ones for h/w with multiple pipelines). > > > > That seems completely upside down and rediculous to me - are you > > really suggesting that we should have some kind of virtual device > > in DT, and omit the _real_ physical devices for that, having the > > driver create the device with all the appropriate SoC resources? > > We create child platform devices that inherit from the parent in DT > all the time. MFD child drivers are a common case. Sometime the child > devices have DT nodes and sometimes they don't. I still don't think what you're saying is the right way to go about this. You _appear_ to be saying to group _both_ LCD controllers into one DT node, despite the fact that they are two separate devices with different mmio resources, interrupts etc, and have code in the kernel to split the DT device up into sub-devices. IOW: lcd-controllers@810000 { compatible = "marvell,dove-lcd-subsystem"; reg = <0x810000 0x1000>, <0x820000 0x1000>; interrupts = <46>, <47>; status = "disabled"; }; rather than: lcd1: lcd-controller@810000 { compatible = "marvell,dove-lcd"; reg = <0x810000 0x1000>; interrupts = <46>; status = "disabled"; }; lcd0: lcd-controller@820000 { compatible = "marvell,dove-lcd"; reg = <0x820000 0x1000>; interrupts = <47>; status = "disabled"; }; Why do we need all that extra complexity, when DT can perfectly well describe each individual LCD controller as a separate node? How do we then do stuff such as: &lcd0 { status = "okay"; clocks = <&si5351 0>; clock-names = "ext_ref_clk1"; lcd0_port: port { lcd0_rgb: endpoint { remote-endpoint = <&tda998x_video>; }; }; }; &lcd1 { status = "okay"; clocks = <÷r_clk 3>; clock-names = "plldivider"; lcd1_port: port { lcd1_rgb: endpoint { remote-endpoint = <&vga_bridge_in>; }; }; }; in board files - we seem to lose a way to reference each individual LCD controller using this method. This is why I say your suggestion is upside down and rather rediculous - it doesn't really fit the hardware at all, and to me just seems to be an exercise in making things unnecessarily difficult. > Otherwise, do it the other way around. Create a virtual DRM device > conditioned on the SoC: > > if (of_machine_is_compatible("foo,bar")) > platform_device_register_simple(...) I guess that's possible at the expense of losing the flexibility - my original idea was to allow a case where you could have two DRM devices, one per LCD controller if you wanted, rather than having a binding that forces one DRM device optionally containing both LCD controllers. This is the flexibility I talk about above, that you seem to have skipped over in your reply. > > > You'll also notice that there are only 3 cases of this virtual node in > > > the tree: STi, i.MX IPU, and Rockchip. That's because we've deprecated > > > doing these virtual nodes for some time now. IOW, there are several > > > examples of how to do this without a virtual node. > > > > This driver has been in-tree with this setup for some time, although > > the documentation has been missing (we actually have a _lot_ of > > instances of that.) However, we have no in-tree DT using it. > > The current Armada DRM driver has no binding to DT at all, so no, it > is not just missing documentation or a dts file. > > > I don't really see how to satisfy your comments without totally > > restructuring the driver, which is going to be quite a big chunk > > of work. I'm not sure I have the motivation to do that right now. > > It's not a big chunk of work. Look at commit 246774d17fc0 > ("drm/etnaviv: remove the need for a gpu-subsystem DT node") for an > example. > > Rob >
On Tue, Jan 22, 2019 at 4:58 AM Russell King - ARM Linux admin <linux@armlinux.org.uk> wrote: > > On Mon, Jan 21, 2019 at 05:58:50PM -0600, Rob Herring wrote: > > On Mon, Jan 21, 2019 at 11:53 AM Russell King - ARM Linux admin > > <linux@armlinux.org.uk> wrote: > > > > > > On Mon, Jan 21, 2019 at 10:07:11AM -0600, Rob Herring wrote: > > > > On Mon, Jan 21, 2019 at 9:46 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > > > > > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > > > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > > > > > nodes that comprise the graphics subsystem. > > > > > > > > > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > > > > > --- > > > > > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > > > > > 1 file changed, 24 insertions(+) > > > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > > > @@ -1,3 +1,27 @@ > > > > > > > +Marvell Armada DRM master device > > > > > > > +================================ > > > > > > > + > > > > > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > > > > > +nodes that comprise the graphics subsystem. > > > > > > > + > > > > > > > +Required properties: > > > > > > > + > > > > > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > > > > > + "marvell,armada-display-subsystem" > > > > > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > > > > > + devices > > > > > > > + - memory-region: phandle to a node describing memory to be used for the > > > > > > > + framebuffer > > > > > > > + > > > > > > > +Example: > > > > > > > + > > > > > > > + display-subsystem { > > > > > > > + compatible = "marvell,dove-display-subsystem", > > > > > > > + "marvell,armada-display-subsystem"; > > > > > > > + memory-region = <&display_reserved>; > > > > > > > + ports = <&lcd0_port>; > > > > > > > > > > > > If there is only one device, you don't need this virtual node. > > > > > > > > > > By "one device" you mean one LCD controller (CRTC)? > > > > > > > > Yes. > > > > > > How does that work (as far as the Linux implementation) ? I can't see > > > a way that could work, while allowing the flexibility that Armada DRM > > > allows (two completely independent LCD controllers as two separate DRM > > > devices vs one DRM device containing both LCD controllers.) > > > > > > > > I suppose in the (single CRTC) example case, the display-subsystem node > > > > > used to associate it with the memory region reserved for allocating the > > > > > frame buffers from. Could that be done differently? > > > > > > > > Move memory-region to the LCD controller node. > > > > > > That doesn't work - it would appear in the wrong part of the driver. > > > > Why? You can fetch properties from other nodes. > > > > If you have 2 CRTCs, do you have 1 or 2 reserved memory regions? I'd > > think 2 with each one in the corresponding LCDC that uses them would > > be more flexible. > > There would still be one reserved memory region, since it is shared > between both LCDCs. > > > Or just get the data out of the /reserved-memory node directly. Surely > > it has a compatible that you can find it with. > > I see that the DT reserved memory support has progressed since I wrote > the armada code to deal with it, and it's now possible to make use of > reserved memory via of_reserved_mem_lookup() rather than using the > RESERVEDMEM_OF_DECLARE() and so forth. > > > > > > Also, if the node is indeed made optional, then it's going to > > > > > complicate things on the DRM side. Currently the driver that binds to > > > > > the node creates the DRM device once it sees all the components > > > > > connected to the ports appear. If we loose it, then the LCD controller > > > > > driver would somehow need to find out that it's alone and create the > > > > > DRM device itself. > > > > > > > > DT is not the only way to create devices. The DRM driver can bind to > > > > the LCDC node and then create a child CRTC device (or even multiple > > > > ones for h/w with multiple pipelines). > > > > > > That seems completely upside down and rediculous to me - are you > > > really suggesting that we should have some kind of virtual device > > > in DT, and omit the _real_ physical devices for that, having the > > > driver create the device with all the appropriate SoC resources? > > > > We create child platform devices that inherit from the parent in DT > > all the time. MFD child drivers are a common case. Sometime the child > > devices have DT nodes and sometimes they don't. > > I still don't think what you're saying is the right way to go about > this. > > You _appear_ to be saying to group _both_ LCD controllers into one > DT node, despite the fact that they are two separate devices with > different mmio resources, interrupts etc, and have code in the > kernel to split the DT device up into sub-devices. IOW: No, not at all. That was just an example of a h/w device having virtual child platform devices. If you want to have 1 DRM device with 2 CRTCs, you have to do as described below. I certainly want this to reflect the h/w. That's why we're having this discussion. [...] > > Otherwise, do it the other way around. Create a virtual DRM device > > conditioned on the SoC: > > > > if (of_machine_is_compatible("foo,bar")) > > platform_device_register_simple(...) > > I guess that's possible at the expense of losing the flexibility - my > original idea was to allow a case where you could have two DRM devices, > one per LCD controller if you wanted, rather than having a binding that > forces one DRM device optionally containing both LCD controllers. Sure, but that's an OS decision that has nothing to do with the hardware and DT. You'll just have to pass some flag to the DRM device platform driver and decide whether to create 1 device or 2. That decision could be based on either evolving DRM architecture or on the platform. That is more flexible than fixing it in DT. Rob
On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > The Marvell Armada DRM master device is a virtual device needed to list all > > nodes that comprise the graphics subsystem. > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > --- > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > 1 file changed, 24 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > index de4cca9432c8..3dbfa8047f0b 100644 > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > @@ -1,3 +1,27 @@ > > +Marvell Armada DRM master device > > +================================ > > + > > +The Marvell Armada DRM master device is a virtual device needed to list all > > +nodes that comprise the graphics subsystem. > > + > > +Required properties: > > + > > + - compatible: value should be "marvell,dove-display-subsystem", > > + "marvell,armada-display-subsystem" > > + - ports: a list of phandles pointing to display interface ports of CRTC > > + devices > > + - memory-region: phandle to a node describing memory to be used for the > > + framebuffer > > + > > +Example: > > + > > + display-subsystem { > > + compatible = "marvell,dove-display-subsystem", > > + "marvell,armada-display-subsystem"; > > + memory-region = <&display_reserved>; > > + ports = <&lcd0_port>; > > If there is only one device, you don't need this virtual node. Before I follow up on this and submit a version without the virtual node, I'm wondering: is it okay that the bindings for the LCDC and the framebuffer are in the same file, or would it be preferrable if they were separate? Both styles seem to be used for the display bindings. > > > > + }; > > + > > Marvell Armada LCD controller > > ============================= > > > > -- > > 2.20.1 Lubo
On Wed, Feb 13, 2019 at 4:37 PM Lubomir Rintel <lkundrak@v3.sk> wrote: > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > nodes that comprise the graphics subsystem. > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > --- > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > 1 file changed, 24 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > @@ -1,3 +1,27 @@ > > > +Marvell Armada DRM master device > > > +================================ > > > + > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > +nodes that comprise the graphics subsystem. > > > + > > > +Required properties: > > > + > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > + "marvell,armada-display-subsystem" > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > + devices > > > + - memory-region: phandle to a node describing memory to be used for the > > > + framebuffer > > > + > > > +Example: > > > + > > > + display-subsystem { > > > + compatible = "marvell,dove-display-subsystem", > > > + "marvell,armada-display-subsystem"; > > > + memory-region = <&display_reserved>; > > > + ports = <&lcd0_port>; > > > > If there is only one device, you don't need this virtual node. > > Before I follow up on this and submit a version without the virtual > node, I'm wondering: is it okay that the bindings for the LCDC and the > framebuffer are in the same file, or would it be preferrable if they > were separate? Both styles seem to be used for the display bindings. framebuffer as in the kernel fbdev? Really, that should be the same binding. It's the same h/w after all. However, there have been cases where things deviated. So I don't have a good answer. Rob
On Fri, 2019-02-22 at 14:23 -0600, Rob Herring wrote: > On Wed, Feb 13, 2019 at 4:37 PM Lubomir Rintel <lkundrak@v3.sk> wrote: > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > > nodes that comprise the graphics subsystem. > > > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > > --- > > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > > 1 file changed, 24 insertions(+) > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > @@ -1,3 +1,27 @@ > > > > +Marvell Armada DRM master device > > > > +================================ > > > > + > > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > > +nodes that comprise the graphics subsystem. > > > > + > > > > +Required properties: > > > > + > > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > > + "marvell,armada-display-subsystem" > > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > > + devices > > > > + - memory-region: phandle to a node describing memory to be used for the > > > > + framebuffer > > > > + > > > > +Example: > > > > + > > > > + display-subsystem { > > > > + compatible = "marvell,dove-display-subsystem", > > > > + "marvell,armada-display-subsystem"; > > > > + memory-region = <&display_reserved>; > > > > + ports = <&lcd0_port>; > > > > > > If there is only one device, you don't need this virtual node. > > > > Before I follow up on this and submit a version without the virtual > > node, I'm wondering: is it okay that the bindings for the LCDC and the > > framebuffer are in the same file, or would it be preferrable if they > > were separate? Both styles seem to be used for the display bindings. > > framebuffer as in the kernel fbdev? Really, that should be the same > binding. It's the same h/w after all. However, there have been cases > where things deviated. So I don't have a good answer. No, not the fbdev device, that one is managed by drmfb and is not expressed in DT. I meant the reserved-memory node that sets aside memory for the framebuffers. See patch "[RFC 03/16] dt-bindings: display: armada: Add framebuffer reserved-mem binding". Perhaps that part should even go to Documentation/devicetree/bindings/reserved-memory/. Lubo
On Sun, Feb 24, 2019 at 10:15 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > On Fri, 2019-02-22 at 14:23 -0600, Rob Herring wrote: > > On Wed, Feb 13, 2019 at 4:37 PM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > On Mon, 2019-01-21 at 09:35 -0600, Rob Herring wrote: > > > > On Sun, Jan 20, 2019 at 11:26 AM Lubomir Rintel <lkundrak@v3.sk> wrote: > > > > > The Marvell Armada DRM master device is a virtual device needed to list all > > > > > nodes that comprise the graphics subsystem. > > > > > > > > > > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> > > > > > --- > > > > > .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ > > > > > 1 file changed, 24 insertions(+) > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > index de4cca9432c8..3dbfa8047f0b 100644 > > > > > --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt > > > > > @@ -1,3 +1,27 @@ > > > > > +Marvell Armada DRM master device > > > > > +================================ > > > > > + > > > > > +The Marvell Armada DRM master device is a virtual device needed to list all > > > > > +nodes that comprise the graphics subsystem. > > > > > + > > > > > +Required properties: > > > > > + > > > > > + - compatible: value should be "marvell,dove-display-subsystem", > > > > > + "marvell,armada-display-subsystem" > > > > > + - ports: a list of phandles pointing to display interface ports of CRTC > > > > > + devices > > > > > + - memory-region: phandle to a node describing memory to be used for the > > > > > + framebuffer > > > > > + > > > > > +Example: > > > > > + > > > > > + display-subsystem { > > > > > + compatible = "marvell,dove-display-subsystem", > > > > > + "marvell,armada-display-subsystem"; > > > > > + memory-region = <&display_reserved>; > > > > > + ports = <&lcd0_port>; > > > > > > > > If there is only one device, you don't need this virtual node. > > > > > > Before I follow up on this and submit a version without the virtual > > > node, I'm wondering: is it okay that the bindings for the LCDC and the > > > framebuffer are in the same file, or would it be preferrable if they > > > were separate? Both styles seem to be used for the display bindings. > > > > framebuffer as in the kernel fbdev? Really, that should be the same > > binding. It's the same h/w after all. However, there have been cases > > where things deviated. So I don't have a good answer. > > No, not the fbdev device, that one is managed by drmfb and is not > expressed in DT. I meant the reserved-memory node that sets aside > memory for the framebuffers. > > See patch "[RFC 03/16] dt-bindings: display: armada: Add framebuffer > reserved-mem binding". Perhaps that part should even go to > Documentation/devicetree/bindings/reserved-memory/. Okay. A separate file will be better and probably Documentation/devicetree/bindings/reserved-memory/ is the best location. Rob
diff --git a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt index de4cca9432c8..3dbfa8047f0b 100644 --- a/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt +++ b/Documentation/devicetree/bindings/display/armada/marvell-armada-drm.txt @@ -1,3 +1,27 @@ +Marvell Armada DRM master device +================================ + +The Marvell Armada DRM master device is a virtual device needed to list all +nodes that comprise the graphics subsystem. + +Required properties: + + - compatible: value should be "marvell,dove-display-subsystem", + "marvell,armada-display-subsystem" + - ports: a list of phandles pointing to display interface ports of CRTC + devices + - memory-region: phandle to a node describing memory to be used for the + framebuffer + +Example: + + display-subsystem { + compatible = "marvell,dove-display-subsystem", + "marvell,armada-display-subsystem"; + memory-region = <&display_reserved>; + ports = <&lcd0_port>; + }; + Marvell Armada LCD controller =============================
The Marvell Armada DRM master device is a virtual device needed to list all nodes that comprise the graphics subsystem. Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> --- .../display/armada/marvell-armada-drm.txt | 24 +++++++++++++++++++ 1 file changed, 24 insertions(+)