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