[PATCH] drm/virtio: Add suppport for non-native

From: Geert Uytterhoeven
Date: Thu Nov 16 2023 - 08:13:55 EST


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>
---
drivers/gpu/drm/virtio/virtgpu_display.c | 11 +++++++++--
drivers/gpu/drm/virtio/virtgpu_plane.c | 6 ++++--
2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_display.c b/drivers/gpu/drm/virtio/virtgpu_display.c
index ad924a8502e9025c..49c89000aec33f23 100644
--- a/drivers/gpu/drm/virtio/virtgpu_display.c
+++ b/drivers/gpu/drm/virtio/virtgpu_display.c
@@ -301,9 +301,16 @@ virtio_gpu_user_framebuffer_create(struct drm_device *dev,
struct virtio_gpu_framebuffer *virtio_gpu_fb;
int ret;

- if (mode_cmd->pixel_format != DRM_FORMAT_HOST_XRGB8888 &&
- mode_cmd->pixel_format != DRM_FORMAT_HOST_ARGB8888)
+ switch (mode_cmd->pixel_format) {
+ case DRM_FORMAT_XRGB8888:
+ case DRM_FORMAT_ARGB8888:
+ case DRM_FORMAT_BGRX8888:
+ case DRM_FORMAT_BGRA8888:
+ break;
+
+ default:
return ERR_PTR(-ENOENT);
+ }

/* lookup object associated with res handle */
obj = drm_gem_object_lookup(file_priv, mode_cmd->handles[0]);
diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index a2e045f3a0004a1b..a547d76b8fb0a77d 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -30,11 +30,13 @@
#include "virtgpu_drv.h"

static const uint32_t virtio_gpu_formats[] = {
- DRM_FORMAT_HOST_XRGB8888,
+ DRM_FORMAT_XRGB8888,
+ DRM_FORMAT_BGRX8888,
};

static const uint32_t virtio_gpu_cursor_formats[] = {
- DRM_FORMAT_HOST_ARGB8888,
+ DRM_FORMAT_ARGB8888,
+ DRM_FORMAT_BGRA8888,
};

uint32_t virtio_gpu_translate_format(uint32_t drm_fourcc)
--
2.34.1