Re: [PATCH 1/3] drm/fourcc: Add missing big-endian XRGB1555 and RGB565 formats
From: Gerd Hoffmann
Date: Tue Jul 12 2022 - 04:39:35 EST
On Tue, Jul 12, 2022 at 10:01:15AM +0200, Geert Uytterhoeven wrote:
> Hi Gerd,
> > 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
Fixed big endian should use 'DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN'.
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.