[PATCH v2 2/2] drm/virtio: Fix host color format for big endian guests

[Jocelyn Falempe <jfalempe@redhat.com>]

The colors are inverted when testing a s390x VM on a s390x host.
Changing the conversion from DRM_FORMAT -> VIRTIO_GPU_FORMAT on big
endian guests fixes the colors. But it may break big-endian guest on
little-endian host. In this case, the fix should be in qemu, because
the host endianess is not known in the guest VM.

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
---
 drivers/gpu/drm/virtio/virtgpu_plane.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index 860b5757ec3fc..0ec6ecc96eb13 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -37,16 +37,24 @@ static const uint32_t virtio_gpu_cursor_formats[] = {
 	DRM_FORMAT_ARGB8888,
 };
 
+#ifdef __BIG_ENDIAN
+#define VIRTIO_GPU_HOST_XRGB8888 VIRTIO_GPU_FORMAT_X8R8G8B8_UNORM
+#define VIRTIO_GPU_HOST_ARGB8888 VIRTIO_GPU_FORMAT_A8R8G8B8_UNORM
+#else
+#define VIRTIO_GPU_HOST_XRGB8888 VIRTIO_GPU_FORMAT_B8G8R8X8_UNORM
+#define VIRTIO_GPU_HOST_ARGB8888 VIRTIO_GPU_FORMAT_B8G8R8A8_UNORM
+#endif
+
 uint32_t virtio_gpu_translate_format(uint32_t drm_fourcc)
 {
 	uint32_t format;
 
 	switch (drm_fourcc) {
 	case DRM_FORMAT_XRGB8888:
-		format = VIRTIO_GPU_FORMAT_B8G8R8X8_UNORM;
+		format = VIRTIO_GPU_HOST_XRGB8888;
 		break;
 	case DRM_FORMAT_ARGB8888:
-		format = VIRTIO_GPU_FORMAT_B8G8R8A8_UNORM;
+		format = VIRTIO_GPU_HOST_ARGB8888;
 		break;
 	default:
 		/*
-- 
2.46.0