On Thu, Nov 16, 2023 at 02:16:54PM +0100, Geert Uytterhoeven wrote:
When using virtgpu on a big-endian machine, e.g. powerpc QEMU:
virtio-pci 0000:00:02.0: [drm] *ERROR* fbdev: Failed to setup generic emulation (ret=-2)
or m68k/virt:
virtio-mmio virtio-mmio.125: [drm] *ERROR* fbdev: Failed to setup generic emulation (ret=-2)
and the graphical display fails to come up.
Before, the call to drm_mode_addfb() caused a translation from a fourcc
format (XR24) to a bpp/depth pair (32/24) to a potentially different fourcc
format (BX24 on big-endian), due to the quirk processing in
drm_driver_legacy_fb_format(). After, the original fourcc format (XR24)
is passed unmodified.
However, the virtgpu DRM driver supports only a single format for its
main plane: DRM_FORMAT_HOST_XRGB8888, which is XR24 on little-endian,
and BX24 on big-endian. I.e. on big-endian, virtgpu does not support
XR24, which is the default DRM format, and must be supported by all
drivers. Before, this was reported, but didn't lead to a failure:
virtio-mmio virtio-mmio.125: [drm] bpp/depth value of 32/24 not supported
virtio-mmio virtio-mmio.125: [drm] No compatible format found
As the core virtgpu driver and device support both XR24 and BX24 on both
little-endian and big-endian just fine, fix this extending the list of
supported formats for main plane and cursor plane to XR24/BX24 resp.
AR24/BA24.
Fixes: 6ae2ff23aa43a0c4 ("drm/client: Convert drm_client_buffer_addfb() to drm_mode_addfb2()")
Reported-by: Christian Zigotzky <chzigotzky@xxxxxxxxxxx>
Closes: https://lore.kernel.org/r/c47fba21-3ae9-4021-9f4a-09c2670ebdbc@xxxxxxxxxxx
Suggested-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Reviewed-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
