Hi Thomas, On Mon, Apr 26, 2021 at 2:22 PM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: > Am 20.04.21 um 11:27 schrieb Geert Uytterhoeven: > > 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? 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@xxxxxxxxxxxxxx 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
