linux-kernel - Re: [PATCH 3/4] drm/tiny: Add driver for Solomon SSD1307 OLED displays

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Date:   Tue, 1 Feb 2022 15:05:18 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Javier Martinez Canillas <javierm@...hat.com>
Cc:     Thomas Zimmermann <tzimmermann@...e.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Noralf Trønnes <noralf@...nnes.org>,
        Maxime Ripard <maxime@...no.tech>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH 3/4] drm/tiny: Add driver for Solomon SSD1307 OLED displays

Hi Javier,

On Tue, Feb 1, 2022 at 2:02 PM Javier Martinez Canillas
<javierm@...hat.com> wrote:
> On 2/1/22 10:33, Thomas Zimmermann wrote:
> >> +{
> >> +    u8 col_end = col_start + cols - 1;
> >> +    int ret;
> >> +
> >> +    if (col_start == ssd1307->col_start && col_end == ssd1307->col_end)
> >> +            return 0;
> >> +
> >> +    ret = ssd1307_write_cmd(ssd1307->client, SSD1307_SET_COL_RANGE);
> >> +    if (ret < 0)
> >> +            return ret;
> >> +
> >> +    ret = ssd1307_write_cmd(ssd1307->client, col_start);
> >> +    if (ret < 0)
> >> +            return ret;
> >> +
> >> +    ret = ssd1307_write_cmd(ssd1307->client, col_end);
> >> +    if (ret < 0)
> >> +            return ret;
> >
> > Can you write these cmds in one step, such as setting up an array and
> > sending it with ssd1307_write_array?
>
> I don't think so because the commands are different. But I'll check the
> ssd1306 datasheet again to confirma that's the case.

IIRC, I tried that while working on the optimizations for ssd1307fb,
and it didn't work.

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