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From: Thomas Zimmermann <tzimmermann@suse.de>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
	Gerd Hoffmann <kraxel@redhat.com>
Cc: 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 14:22:20 +0200	[thread overview]
Message-ID: <e2d46fc0-5452-5d13-0354-e2e9bd407139@suse.de> (raw)
In-Reply-To: <CAMuHMdX=0H3LHP5Yme9tpN4JnmpJcnF=SQN8bc=4XTd-X6AVTg@mail.gmail.com>


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Hi

Am 20.04.21 um 11:27 schrieb Geert Uytterhoeven:
> 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 ;-)

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?

Best regards
Thomas

> 
> Gr{oetje,eeting}s,
> 
>                          Geert
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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  reply	other threads:[~2021-04-26 12:22 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 [this message]
2021-04-26 19:05           ` Geert Uytterhoeven
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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