summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/gpu/drm/virtio/virtgpu_drm_bus.c')
-rw-r--r--drivers/gpu/drm/virtio/virtgpu_drm_bus.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/drivers/gpu/drm/virtio/virtgpu_drm_bus.c b/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
index 757ca28ab93e..0887e0b64b9c 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
@@ -53,6 +53,37 @@ int drm_virtio_init(struct drm_driver *driver, struct virtio_device *vdev)
0,
"virtiodrmfb");
+ /*
+ * Normally the drm_dev_set_unique() call is done by core DRM.
+ * The following comment covers, why virtio cannot rely on it.
+ *
+ * Unlike the other virtual GPU drivers, virtio abstracts the
+ * underlying bus type by using struct virtio_device.
+ *
+ * Hence the dev_is_pci() check, used in core DRM, will fail
+ * and the unique returned will be the virtio_device "virtio0",
+ * while a "pci:..." one is required.
+ *
+ * A few other ideas were considered:
+ * - Extend the dev_is_pci() check [in drm_set_busid] to
+ * consider virtio.
+ * Seems like a bigger hack than what we have already.
+ *
+ * - Point drm_device::dev to the parent of the virtio_device
+ * Semantic changes:
+ * * Using the wrong device for i2c, framebuffer_alloc and
+ * prime import.
+ * Visual changes:
+ * * Helpers such as DRM_DEV_ERROR, dev_info, drm_printer,
+ * will print the wrong information.
+ *
+ * We could address the latter issues, by introducing
+ * drm_device::bus_dev, ... which would be used solely for this.
+ *
+ * So for the moment keep things as-is, with a bulky comment
+ * for the next person who feels like removing this
+ * drm_dev_set_unique() quirk.
+ */
snprintf(unique, sizeof(unique), "pci:%s", pname);
ret = drm_dev_set_unique(dev, unique);
if (ret)