Geert Uytterhoeven
2021-Apr-20 09:27 UTC
[PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs
Hi Gerd, On Tue, Apr 20, 2021 at 11:22 AM Gerd Hoffmann <kraxel at 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 at 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
Thomas Zimmermann
2021-Apr-26 12:22 UTC
[PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs
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 at 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 N?rnberg, Germany (HRB 36809, AG N?rnberg) Gesch?ftsf?hrer: Felix Imend?rffer -------------- next part -------------- A non-text attachment was scrubbed... Name: OpenPGP_signature Type: application/pgp-signature Size: 840 bytes Desc: OpenPGP digital signature URL: <http://lists.linuxfoundation.org/pipermail/virtualization/attachments/20210426/4fcc0c80/attachment.sig>