On 3/15/22 01:42, Dmitry Osipenko wrote:
DRM API requires the DRM's driver to be backed with the device that can be used for generic DMA operations. The VirtIO-GPU device can't perform DMA operations if it uses PCI transport because PCI device driver creates a virtual VirtIO-GPU device that isn't associated with the PCI. Use PCI's GPU device for the DRM's device instead of the VirtIO-GPU device and drop DMA-related hacks from the VirtIO-GPU driver.
Signed-off-by: Dmitry Osipenko dmitry.osipenko@collabora.com
drivers/gpu/drm/virtio/virtgpu_drv.c | 22 +++++++--- drivers/gpu/drm/virtio/virtgpu_drv.h | 5 +-- drivers/gpu/drm/virtio/virtgpu_kms.c | 7 ++-- drivers/gpu/drm/virtio/virtgpu_object.c | 56 +++++-------------------- drivers/gpu/drm/virtio/virtgpu_vq.c | 13 +++--- 5 files changed, 37 insertions(+), 66 deletions(-)
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c index 5f25a8d15464..8449dad3e65c 100644 --- a/drivers/gpu/drm/virtio/virtgpu_drv.c +++ b/drivers/gpu/drm/virtio/virtgpu_drv.c @@ -46,9 +46,9 @@ static int virtio_gpu_modeset = -1; MODULE_PARM_DESC(modeset, "Disable/Enable modesetting"); module_param_named(modeset, virtio_gpu_modeset, int, 0400);
-static int virtio_gpu_pci_quirk(struct drm_device *dev, struct virtio_device *vdev) +static int virtio_gpu_pci_quirk(struct drm_device *dev)
Somehow I missed that virtio_gpu_pci_quirk() contains comment telling about why dev.parent isn't used for the DRM's device.
/* * 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. */
There is no I2C, nor prime import support and framebuffer_alloc hasn't been used for years now. I guess prime import actually will want the real device and not the virtio_device if GEM importing will be ever supported by VirtIO-GPU driver. Apparently this comment was outdated a long time ago and the "visual changes" aren't too important, the messages now says "virtio-pci 0000:00:02.0" instead of "virtio_gpu virtio0".
I'll remove the comment and drm_dev_set_unique() quirk in v3.