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[resend,0/5] video: fbdev: ssd1307fb: Optimizations and improvements

Message ID 20210714145804.2530727-1-geert@linux-m68k.org (mailing list archive)
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Series video: fbdev: ssd1307fb: Optimizations and improvements | expand

Message

Geert Uytterhoeven July 14, 2021, 2:57 p.m. UTC
Hi all,

This patch series optimizes console operations on ssd1307fb, after the
customary fixes and cleanups.

Currently, each screen update triggers an I2C transfer of all screen
data, up to 1 KiB of data for a 128x64 display, which takes at least 20
ms in Fast mode.  While many displays are smaller, and thus require less
data to be transferred, 20 ms is still an optimistic value, as the
actual data transfer may be much slower, especially on bitbanged I2C
drivers.  After this series, the amount of data transfer is reduced, as
fillrect, copyarea, and imageblit only update the rectangle that
changed.

This has been tested on an Adafruit FeatherWing OLED with an SSD1306
controller and a 128x32 OLED, connected to an OrangeCrab ECP5 FPGA board
running a 64 MHz VexRiscv RISC-V softcore, where it reduced the CPU
usage for blinking the cursor from more than 70% to ca. 10%.

Thanks for your comments!

Geert Uytterhoeven (5):
  video: fbdev: ssd1307fb: Propagate errors via
    ssd1307fb_update_display()
  video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display()
  video: fbdev: ssd1307fb: Extract ssd1307fb_set_address_range()
  video: fbdev: ssd1307fb: Optimize screen updates
  video: fbdev: ssd1307fb: Cache address ranges

 drivers/video/fbdev/ssd1307fb.c | 143 +++++++++++++++++++++-----------
 1 file changed, 96 insertions(+), 47 deletions(-)

Comments

Sam Ravnborg July 14, 2021, 3:27 p.m. UTC | #1
Hi Geert,

On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> 	Hi all,
> 
> This patch series optimizes console operations on ssd1307fb, after the
> customary fixes and cleanups.

What is required to to have a drm driver that could do the same?

Note: I will take a look at the patches a bit later.

	Sam
Geert Uytterhoeven July 15, 2021, 6:54 a.m. UTC | #2
Hi Sam,

On Wed, Jul 14, 2021 at 5:27 PM Sam Ravnborg <sam@ravnborg.org> wrote:
> On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> > This patch series optimizes console operations on ssd1307fb, after the
> > customary fixes and cleanups.
>
> What is required to to have a drm driver that could do the same?

Add monochrome support to DRM?

> Note: I will take a look at the patches a bit later.

TIA!

Gr{oetje,eeting}s,

                        Geert
Sam Ravnborg July 19, 2021, 7:23 p.m. UTC | #3
Hi Geert,

On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> 	Hi all,
> 
> This patch series optimizes console operations on ssd1307fb, after the
> customary fixes and cleanups.
> 
> Currently, each screen update triggers an I2C transfer of all screen
> data, up to 1 KiB of data for a 128x64 display, which takes at least 20
> ms in Fast mode.  While many displays are smaller, and thus require less
> data to be transferred, 20 ms is still an optimistic value, as the
> actual data transfer may be much slower, especially on bitbanged I2C
> drivers.  After this series, the amount of data transfer is reduced, as
> fillrect, copyarea, and imageblit only update the rectangle that
> changed.
> 
> This has been tested on an Adafruit FeatherWing OLED with an SSD1306
> controller and a 128x32 OLED, connected to an OrangeCrab ECP5 FPGA board
> running a 64 MHz VexRiscv RISC-V softcore, where it reduced the CPU
> usage for blinking the cursor from more than 70% to ca. 10%.
> 
> Thanks for your comments!
> 
> Geert Uytterhoeven (5):
>   video: fbdev: ssd1307fb: Propagate errors via
>     ssd1307fb_update_display()
>   video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display()
>   video: fbdev: ssd1307fb: Extract ssd1307fb_set_address_range()
>   video: fbdev: ssd1307fb: Optimize screen updates
>   video: fbdev: ssd1307fb: Cache address ranges

A few comments left for a couple of patches.
The remaining patches are:
Acked-by: Sam Ravnborg <sam@ravnborg.org>

Do you have commit rights to drm-misc-next?

	Sam
Geert Uytterhoeven July 20, 2021, 7:33 a.m. UTC | #4
Hi Sam,

On Mon, Jul 19, 2021 at 9:23 PM Sam Ravnborg <sam@ravnborg.org> wrote:
> On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> > This patch series optimizes console operations on ssd1307fb, after the
> > customary fixes and cleanups.
> >
> > Currently, each screen update triggers an I2C transfer of all screen
> > data, up to 1 KiB of data for a 128x64 display, which takes at least 20
> > ms in Fast mode.  While many displays are smaller, and thus require less
> > data to be transferred, 20 ms is still an optimistic value, as the
> > actual data transfer may be much slower, especially on bitbanged I2C
> > drivers.  After this series, the amount of data transfer is reduced, as
> > fillrect, copyarea, and imageblit only update the rectangle that
> > changed.
> >
> > This has been tested on an Adafruit FeatherWing OLED with an SSD1306
> > controller and a 128x32 OLED, connected to an OrangeCrab ECP5 FPGA board
> > running a 64 MHz VexRiscv RISC-V softcore, where it reduced the CPU
> > usage for blinking the cursor from more than 70% to ca. 10%.
> >
> > Thanks for your comments!
> >
> > Geert Uytterhoeven (5):
> >   video: fbdev: ssd1307fb: Propagate errors via
> >     ssd1307fb_update_display()
> >   video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display()
> >   video: fbdev: ssd1307fb: Extract ssd1307fb_set_address_range()
> >   video: fbdev: ssd1307fb: Optimize screen updates
> >   video: fbdev: ssd1307fb: Cache address ranges
>
> A few comments left for a couple of patches.
> The remaining patches are:
> Acked-by: Sam Ravnborg <sam@ravnborg.org>

Thank you!

> Do you have commit rights to drm-misc-next?

No I have not (and I don't think I should).

Gr{oetje,eeting}s,

                        Geert
Sam Ravnborg July 20, 2021, 2:45 p.m. UTC | #5
Hi Geert,
On Tue, Jul 20, 2021 at 09:33:11AM +0200, Geert Uytterhoeven wrote:
> Hi Sam,
> 
> On Mon, Jul 19, 2021 at 9:23 PM Sam Ravnborg <sam@ravnborg.org> wrote:
> > On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> > > This patch series optimizes console operations on ssd1307fb, after the
> > > customary fixes and cleanups.
> > >
> > > Currently, each screen update triggers an I2C transfer of all screen
> > > data, up to 1 KiB of data for a 128x64 display, which takes at least 20
> > > ms in Fast mode.  While many displays are smaller, and thus require less
> > > data to be transferred, 20 ms is still an optimistic value, as the
> > > actual data transfer may be much slower, especially on bitbanged I2C
> > > drivers.  After this series, the amount of data transfer is reduced, as
> > > fillrect, copyarea, and imageblit only update the rectangle that
> > > changed.
> > >
> > > This has been tested on an Adafruit FeatherWing OLED with an SSD1306
> > > controller and a 128x32 OLED, connected to an OrangeCrab ECP5 FPGA board
> > > running a 64 MHz VexRiscv RISC-V softcore, where it reduced the CPU
> > > usage for blinking the cursor from more than 70% to ca. 10%.
> > >
> > > Thanks for your comments!
> > >
> > > Geert Uytterhoeven (5):
> > >   video: fbdev: ssd1307fb: Propagate errors via
> > >     ssd1307fb_update_display()
> > >   video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display()
> > >   video: fbdev: ssd1307fb: Extract ssd1307fb_set_address_range()
> > >   video: fbdev: ssd1307fb: Optimize screen updates
> > >   video: fbdev: ssd1307fb: Cache address ranges
> >
> > A few comments left for a couple of patches.
> > The remaining patches are:
> > Acked-by: Sam Ravnborg <sam@ravnborg.org>
> 
> Thank you!
> 
> > Do you have commit rights to drm-misc-next?
> 
> No I have not (and I don't think I should).
I would love to have you around for the fbdev stuff, as you knows a ton
more about fbdev than I do - I am just pretending.
And it would then be good if you could apply patches too. I for one may
be off for shorter or longer periods as this is purely driven by interest.

Note: I assume you will resend the series - then I can apply.

	Sam
Daniel Vetter July 20, 2021, 2:53 p.m. UTC | #6
On Thu, Jul 15, 2021 at 8:54 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Sam,
>
> On Wed, Jul 14, 2021 at 5:27 PM Sam Ravnborg <sam@ravnborg.org> wrote:
> > On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> > > This patch series optimizes console operations on ssd1307fb, after the
> > > customary fixes and cleanups.
> >
> > What is required to to have a drm driver that could do the same?
>
> Add monochrome support to DRM?

I think the bits that are missing for that are
- wiring up the conversion from R* formats to their fbdev counterparts
in the emulation helper (if you want to support userspace sending the
native format directly through fbdev

Everything else is there and we have drivers doing this, e.g.
drm/tiny/repaper.c.
-Daniel

>
> > Note: I will take a look at the patches a bit later.
>
> TIA!
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds