Messages in this thread | | | Date | Tue, 7 Mar 2023 21:25:13 +0300 | Subject | Re: [PATCH v12 10/11] drm/virtio: Support memory shrinking | From | Dmitry Osipenko <> |
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On 3/7/23 13:42, Thomas Zimmermann wrote: > Hi > > Am 05.03.23 um 23:10 schrieb Dmitry Osipenko: > [...] >> *bo_ptr = bo; >> diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c >> b/drivers/gpu/drm/virtio/virtgpu_plane.c >> index 4c09e313bebc..3f21512ff153 100644 >> --- a/drivers/gpu/drm/virtio/virtgpu_plane.c >> +++ b/drivers/gpu/drm/virtio/virtgpu_plane.c >> @@ -238,20 +238,32 @@ static int virtio_gpu_plane_prepare_fb(struct >> drm_plane *plane, >> struct virtio_gpu_device *vgdev = dev->dev_private; >> struct virtio_gpu_framebuffer *vgfb; >> struct virtio_gpu_object *bo; >> + int err; >> if (!new_state->fb) >> return 0; >> vgfb = to_virtio_gpu_framebuffer(new_state->fb); >> bo = gem_to_virtio_gpu_obj(vgfb->base.obj[0]); >> - if (!bo || (plane->type == DRM_PLANE_TYPE_PRIMARY && >> !bo->guest_blob)) >> + >> + if (virtio_gpu_is_shmem(bo)) { > > Not really a problem with this patchset, but having such branches looks > like a bug in the driver's GEM design. Whatever your GEM object needs or > does, it should be hidden in the implementation. Why is virtio doing this?
There is another "VRAM" VirtIO-GPU BO type that doesn't implement the pin/unpin callbacks. Perhaps another option was to add the callbacks.
>> + err = drm_gem_pin(&bo->base.base); > > As the driver uses GEM SHMEM, please call drm_gem_shmem_object_pin() > directly and remove patch [09/11]. Same goes for the _unpin call below. > > The problem with generic pinning interfaces is that there's no way of > specifying where to pin to BO. The problem is most apparent with TTM, > where hardware often has multiple locations were buffer can be placed > (VRAM, GART, system memory). So it's really a detail between the driver > and the memory manager. > > These generic internal GEM interfaces should only be used by DRM core > and helpers. Drivers should use their memory manager's interface.
I'll switch to use drm_gem_shmem_object_pin() directly in v13, maybe add virtio_gpu_gem_pin() helper for that. Thanks!
-- Best regards, Dmitry
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