linux-kernel - Re: [PATCH resend 0/5] video: fbdev: ssd1307fb: Optimizations and improvements

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Date:   Tue, 20 Jul 2021 09:33:11 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Sam Ravnborg <sam@...nborg.org>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Maxime Ripard <mripard@...nel.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH resend 0/5] video: fbdev: ssd1307fb: Optimizations and improvements

Hi Sam,

On Mon, Jul 19, 2021 at 9:23 PM Sam Ravnborg <sam@...nborg.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@...nborg.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

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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