From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Gerd Hoffmann <kraxel@redhat.com>,
bluescreen_avenger@verizon.net, Jonathan Corbet <corbet@lwn.net>,
David Airlie <airlied@linux.ie>,
Emil Velikov <emil.l.velikov@gmail.com>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Liam Girdwood <lgirdwood@gmail.com>,
virtualization@lists.linux-foundation.org,
Hans de Goede <hdegoede@redhat.com>,
Mark Brown <broonie@kernel.org>,
DRI Development <dri-devel@lists.freedesktop.org>,
Greg KH <gregkh@linuxfoundation.org>,
Sam Ravnborg <sam@ravnborg.org>
Subject: Re: [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs
Date: Mon, 26 Apr 2021 21:05:28 +0200 [thread overview]
Message-ID: <CAMuHMdW6HQCZYXS3N+xh4xPQqdKix9dP3vcMU49NJ95179BR9g@mail.gmail.com> (raw)
In-Reply-To: <e2d46fc0-5452-5d13-0354-e2e9bd407139@suse.de>
Hi Thomas,
On Mon, Apr 26, 2021 at 2:22 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> Am 20.04.21 um 11:27 schrieb Geert Uytterhoeven:
> > 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 ;-)
>
> I vaguely remember that HAM mode uses some crazy format where pixel
> colors depend in the values of their neighbors. (?) How complicated is
> it to write a conversion from RGB to HAM?
Not that complicated, unless you want to do it Good & Fast ;-)
https://en.wikipedia.org/wiki/Hold-And-Modify
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
next prev parent reply other threads:[~2021-04-26 19:05 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-16 9:00 [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip() Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 2/9] drm/format-helper: Add blitter functions Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 3/9] drm/aperture: Add infrastructure for aperture ownership Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 4/9] drm: Add simpledrm driver Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 5/9] drm/simpledrm: Add fbdev emulation Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 6/9] drm/simpledrm: Initialize framebuffer data from device-tree node Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 7/9] drm/simpledrm: Acquire clocks from DT device node Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 8/9] drm/simpledrm: Acquire regulators " Thomas Zimmermann
2021-04-16 9:00 ` [PATCH v4 9/9] drm/simpledrm: Acquire memory aperture for framebuffer Thomas Zimmermann
2021-04-19 8:00 ` [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs Geert Uytterhoeven
2021-04-20 8:46 ` Daniel Vetter
2021-04-20 9:16 ` Geert Uytterhoeven
2021-04-20 11:11 ` Daniel Vetter
2021-04-20 9:22 ` Gerd Hoffmann
2021-04-20 9:27 ` Geert Uytterhoeven
2021-04-26 12:22 ` Thomas Zimmermann
2021-04-26 19:05 ` Geert Uytterhoeven [this message]
2021-04-26 12:18 ` Thomas Zimmermann
2021-04-26 15:08 ` Daniel Vetter
2021-04-29 10:24 ` Maxime Ripard
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