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@xxxxxxxxxx> 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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