Re: [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs

Geert Uytterhoeven
2021-04-20T09:28:14Z

Hi Gerd,

On Tue, Apr 20, 2021 at 11:22 AM Gerd Hoffmann <kraxel@redhat.com> wrote:
> > > > Patches 4 to 8 add the simpledrm driver. It's build on simple DRM helpers
> > > > and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
> > >
> > > .... if support for 8-bit frame buffers would be added?
> >
> > Is that 8-bit greyscale or 8-bit indexed with 256 entry palette? Former
> > shouldn't be a big thing, but the latter is only really supported by the
> > overall drm ecosystem in theory. Most userspace assumes that xrgb8888
> > works, and we keep that illusion up by emulating it in kernel for hw which
> > just doesn't support it. But reformatting xrgb8888 to c8 is tricky at
> > best.
>
> Well. cirrus converts xrgb8888 on the fly to rgb888 or rgb565
> (depending on display resolution). We could pull off the same trick
> here and convert to rgb332 (assuming we can program the palette with the
> color cube needed for that). Wouldn't look pretty, but would probably
> work better than expecting userspace know what color palettes are in
> 2021 ...

Yeah, I already had a similar idea for Amiga HAM ;-)

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