Re: [PATCH] drm/virtio: add ARGB8888 support for primary planes

[Thomas Zimmermann]

Am 30.09.26 um 18:12 schrieb Dorinda Bassey:
> Hi Thomas,
>
>     But does the host also support ARGB on the primary plane? We usually
>     don't export formats that are not available in (virtual) hardware.
>
>
> If you're asking about the hypervisor side providing the Virtual GPU,
> Yes the host supports ARGB on primary plane. QEMU's virtio-gpu

Ok, thanks.

Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>


> supports this see qemu's include/hw/virtio/virtio-gpu-pixman.h:26
> libkrun's virtio-gpu includes `B8G8R8A8_UNORM` in its
> ResourceFormat enum and maps it to display backend formats.
> Virglrenderer, which vhost-device-gpu also uses, maps
> `GBM_FORMAT_ARGB8888` to `VIRGL_FORMAT_B8G8R8A8_UNORM`.
> Other VMMs I've tested also support this format.
>
> Also I see the cursor plane in the virtio-gpu driver already exposes
> `DRM_FORMAT_HOST_ARGB8888`, confirming existing ARGB support
> in backends. I tested this with the vhost-user-gpu backend from -
> https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-gpu
> and the libkrun guest, glmark2-drm renders correctly with it.
>
> BR,
> Dorinda.
>
>
> On Wed, Sep 30, 2026 at 5:04 PM Thomas Zimmermann 
> <tzimmermann@xxxxxxx> wrote:
>
>     Hi
>
>     Am 30.09.26 um 15:27 schrieb Dorinda Bassey:
>     > Add DRM_FORMAT_HOST_ARGB8888 to the list of supported formats for
>     > virtio-gpu primary planes. Without this, glmark2-drm fails at
>     > startup because it selects ARGB visual configs by default, which
>     > don't match the XRGB-only plane capabilities. This causes
>     > drmModeSetCrtc to fail with EINVAL.
>
>     But does the host also support ARGB on the primary plane? We usually
>     don't export formats that are not available in (virtual) hardware.
>
>     Best regards
>     Thomas
>
>     >
>     > The virtio_gpu_translate_format() function already handles
>     > ARGB8888 translation to VIRTIO_GPU_FORMAT_B8G8R8A8_UNORM,
>     > so this just exposes the existing capability to userspace.
>     >
>     > Signed-off-by: Dorinda Bassey <dbassey@xxxxxxxxxx>
>     > ---
>     >   drivers/gpu/drm/virtio/virtgpu_plane.c | 1 +
>     >   1 file changed, 1 insertion(+)
>     >
>     > diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c
>     b/drivers/gpu/drm/virtio/virtgpu_plane.c
>     > index b422eba42a5f..5f0bc1b1931b 100644
>     > --- a/drivers/gpu/drm/virtio/virtgpu_plane.c
>     > +++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
>     > @@ -37,6 +37,7 @@
>     >
>     >   static const uint32_t virtio_gpu_formats[] = {
>     >       DRM_FORMAT_HOST_XRGB8888,
>     > +     DRM_FORMAT_HOST_ARGB8888,
>     >   };
>     >
>     >   static const uint32_t virtio_gpu_cursor_formats[] = {
>
>     -- 
>     --
>     Thomas Zimmermann
>     Graphics Driver Developer
>     SUSE Software Solutions Germany GmbH
>     Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
>     <http://www.suse.com>
>     GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG
>     Nürnberg)

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)