Hi Gerd,
On Tue, Jul 12, 2022 at 10:39 AM Gerd Hoffmann <kraxel@xxxxxxxxxx> wrote:
On Tue, Jul 12, 2022 at 10:01:15AM +0200, Geert Uytterhoeven wrote:
It IMHO is not applicable to any physical hardware. It's used by
virtio-gpu where the supported format depends on the byte order
(it is argb8888 in native byte order). Only virtual hardware can
have that kind of behavior.
And we can probably drop the DRM_FORMAT_HOST_* variants for 1555 and
565, they are not used anywhere.
Atari DRM supports (big-endian) RGB565, so it uses
DRM_FORMAT_HOST_RGB565.
Fixed big endian should use 'DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN'.
True.
As described above DRM_FORMAT_HOST_RGB565 means bigendian on bigendian
hosts and little endian on little endian hosts. Which is not correct
when your hardware does big endian no matter what.
But (a) drm_driver_legacy_fb_format() uses DRM_FORMAT_HOST_RGB565
if quirk_addfb_prefer_host_byte_order is set, and (b)
quirk_addfb_prefer_host_byte_order must be set on big-endian as
per commit eae06120f1974e1a ("drm: refuse ADDFB2 ioctl for broken
bigendian drivers").
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
