linux-fbdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Maxime Ripard <mripard@kernel.org>,
	Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH resend 4/5] video: fbdev: ssd1307fb: Optimize screen updates
Date: Tue, 20 Jul 2021 09:56:52 +0200	[thread overview]
Message-ID: <CAMuHMdVyuzQzXF0X3OA=PH4E4ifaT2TfHs76yGgRKk-XrEbwzw@mail.gmail.com> (raw)
In-Reply-To: <YPXQnlpWUa1QaZKd@ravnborg.org>

Hi Sam,

On Mon, Jul 19, 2021 at 9:21 PM Sam Ravnborg <sam@ravnborg.org> wrote:
> On Wed, Jul 14, 2021 at 04:58:03PM +0200, Geert Uytterhoeven wrote:
> > 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.
> >
> > Reduce the amount of transferred data by only updating the rectangle
> > that changed.  Remove the call to ssd1307fb_set_address_range() during
> > initialization, as ssd1307fb_update_rect() now takes care of that.
> >
> > Note that for now the optimized operation is only used for fillrect,
> > copyarea, and imageblit, which are used by fbcon.
> >
> > Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

> > --- a/drivers/video/fbdev/ssd1307fb.c
> > +++ b/drivers/video/fbdev/ssd1307fb.c
> > @@ -184,16 +184,18 @@ static int ssd1307fb_set_address_range(struct ssd1307fb_par *par, u8 col_start,
> >       return ssd1307fb_write_cmd(par->client, page_end);
> >  }
> >
> > -static int ssd1307fb_update_display(struct ssd1307fb_par *par)
> > +static int ssd1307fb_update_rect(struct ssd1307fb_par *par, unsigned int x,
> > +                              unsigned int y, unsigned int width,
> > +                              unsigned int height)
> >  {
> >       struct ssd1307fb_array *array;
> >       u8 *vmem = par->info->screen_buffer;
> >       unsigned int line_length = par->info->fix.line_length;
> > -     unsigned int pages = DIV_ROUND_UP(par->height, 8);
> > +     unsigned int pages = DIV_ROUND_UP(height + y % 8, 8);
>
> Add () like this - at least it helps me:
> > +     unsigned int pages = DIV_ROUND_UP((height + y) % 8, 8);

Thanks, that's actually a genuine bug.

> > @@ -226,13 +228,18 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par)
> >        *  (5) A4 B4 C4 D4 E4 F4 G4 H4
> >        */
> >
> > -     for (i = 0; i < pages; i++) {
> > +     ret = ssd1307fb_set_address_range(par, par->col_offset + x, width,
> > +                                       par->page_offset + y / 8, pages);
> > +     if (ret < 0)
> > +             goto out_free;
> > +
> > +     for (i = y / 8; i < y / 8 + pages; i++) {
> >               int m = 8;
> >
> >               /* Last page may be partial */
> > -             if (i + 1 == pages && par->height % 8)
> > +             if (8 * (i + 1) > par->height)
> >                       m = par->height % 8;
> As before, this looks wrong to me.

Let's sort that out in the other thread...

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

  parent reply	other threads:[~2021-07-20  7:57 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14 14:57 [PATCH resend 0/5] video: fbdev: ssd1307fb: Optimizations and improvements Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 1/5] video: fbdev: ssd1307fb: Propagate errors via ssd1307fb_update_display() Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 2/5] video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display() Geert Uytterhoeven
     [not found]   ` <YPXM8AXNje7GXf+i@ravnborg.org>
2021-07-20  7:43     ` Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 3/5] video: fbdev: ssd1307fb: Extract ssd1307fb_set_address_range() Geert Uytterhoeven
     [not found]   ` <YPXNdJNpYoPSpxSb@ravnborg.org>
2021-07-20  7:51     ` Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 4/5] video: fbdev: ssd1307fb: Optimize screen updates Geert Uytterhoeven
     [not found]   ` <YPXQnlpWUa1QaZKd@ravnborg.org>
2021-07-20  7:56     ` Geert Uytterhoeven [this message]
2021-07-20  9:16       ` Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 5/5] video: fbdev: ssd1307fb: Cache address ranges Geert Uytterhoeven
     [not found] ` <YO8CT+Hcw1wfhnH5@ravnborg.org>
2021-07-15  6:54   ` [PATCH resend 0/5] video: fbdev: ssd1307fb: Optimizations and improvements Geert Uytterhoeven
2021-07-20 14:53     ` Daniel Vetter
     [not found] ` <YPXRMXQxCW+Agaz8@ravnborg.org>
2021-07-20  7:33   ` Geert Uytterhoeven

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAMuHMdVyuzQzXF0X3OA=PH4E4ifaT2TfHs76yGgRKk-XrEbwzw@mail.gmail.com' \
    --to=geert@linux-m68k.org \
    --cc=airlied@linux.ie \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=linux-fbdev@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mripard@kernel.org \
    --cc=sam@ravnborg.org \
    --subject='Re: [PATCH resend 4/5] video: fbdev: ssd1307fb: Optimize screen updates' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).