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drm/virtio: Improve DMA API usage for shmem BOs

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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>
Link: http://patchwork.freedesktop.org/patch/msgid/20220630200726.1884320-8-dmitry.osipenko@collabora.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Dmitry Osipenko
2022-06-30 23:07:24 +03:00
committed by Gerd Hoffmann
parent e7fef09233
commit b5c9ed70d1
5 changed files with 32 additions and 99 deletions
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51
drivers/gpu/drm/virtio/virtgpu_drv.c
View File

@@ -46,12 +46,11 @@ 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)
{
struct pci_dev *pdev = to_pci_dev(vdev->dev.parent);
struct pci_dev *pdev = to_pci_dev(dev->dev);
const char *pname = dev_name(&pdev->dev);
bool vga = (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;
char unique[20];
int ret;
DRM_INFO("pci: %s detected at %s\n",
@@ -63,39 +62,7 @@ static int virtio_gpu_pci_quirk(struct drm_device *dev, struct virtio_device *vd
return ret;
}
/*
* 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);
return drm_dev_set_unique(dev, unique);
return 0;
}
static int virtio_gpu_probe(struct virtio_device *vdev)
@@ -109,18 +76,24 @@ static int virtio_gpu_probe(struct virtio_device *vdev)
if (virtio_gpu_modeset == 0)
return -EINVAL;
dev = drm_dev_alloc(&driver, &vdev->dev);
/*
* The virtio-gpu device is a virtual device that doesn't have DMA
* ops assigned to it, nor DMA mask set and etc. Its parent device
* is actual GPU device we want to use it for the DRM's device in
* order to benefit from using generic DRM APIs.
*/
dev = drm_dev_alloc(&driver, vdev->dev.parent);
if (IS_ERR(dev))
return PTR_ERR(dev);
vdev->priv = dev;
if (!strcmp(vdev->dev.parent->bus->name, "pci")) {
ret = virtio_gpu_pci_quirk(dev, vdev);
ret = virtio_gpu_pci_quirk(dev);
if (ret)
goto err_free;
}
ret = virtio_gpu_init(dev);
ret = virtio_gpu_init(vdev, dev);
if (ret)
goto err_free;