Hi Dmitry,
> Subject: [PATCH v3 2/2] drm/virtio: New fence for every plane update
>
> From: Dongwon Kim <dongwon....@intel.com>
>
> Having a fence linked to a virtio_gpu_framebuffer in the plane update
> sequence would cause conflict when several planes referencing the same
> framebuffer (e.g. Xorg screen covering multi-displays configured for an
> extended mode) and those planes are updated concurrently. So it is needed
> to allocate a fence for every plane state instead of the framebuffer.
>
> Signed-off-by: Dongwon Kim <dongwon....@intel.com>
> [dmitry.osipe...@collabora.com: rebase, fix up, edit commit message]
> Signed-off-by: Dmitry Osipenko <dmitry.osipe...@collabora.com>
> ---
> drivers/gpu/drm/virtio/virtgpu_drv.h | 7 ++++
> drivers/gpu/drm/virtio/virtgpu_plane.c | 58 +++++++++++++++++---------
> 2 files changed, 46 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h
> b/drivers/gpu/drm/virtio/virtgpu_drv.h
> index 64c236169db8..5dc8eeaf7123 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> @@ -194,6 +194,13 @@ struct virtio_gpu_framebuffer {
> #define to_virtio_gpu_framebuffer(x) \
> container_of(x, struct virtio_gpu_framebuffer, base)
>
> +struct virtio_gpu_plane_state {
> + struct drm_plane_state base;
> + struct virtio_gpu_fence *fence;
> +};
> +#define to_virtio_gpu_plane_state(x) \
> + container_of(x, struct virtio_gpu_plane_state, base)
> +
> struct virtio_gpu_queue {
> struct virtqueue *vq;
> spinlock_t qlock;
> diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c
> b/drivers/gpu/drm/virtio/virtgpu_plane.c
> index ab7232921cb7..2add67c6b66d 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_plane.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
> @@ -67,11 +67,28 @@ uint32_t virtio_gpu_translate_format(uint32_t
> drm_fourcc)
> return format;
> }
>
> +static struct
> +drm_plane_state *virtio_gpu_plane_duplicate_state(struct drm_plane
> *plane)
> +{
> + struct virtio_gpu_plane_state *new;
> +
> + if (WARN_ON(!plane->state))
> + return NULL;
> +
> + new = kzalloc(sizeof(*new), GFP_KERNEL);
> + if (!new)
> + return NULL;
> +
> + __drm_atomic_helper_plane_duplicate_state(plane, &new->base);
> +
> + return &new->base;
> +}
> +
> static const struct drm_plane_funcs virtio_gpu_plane_funcs = {
> .update_plane = drm_atomic_helper_update_plane,
> .disable_plane = drm_atomic_helper_disable_plane,
> .reset = drm_atomic_helper_plane_reset,
> - .atomic_duplicate_state =
> drm_atomic_helper_plane_duplicate_state,
> + .atomic_duplicate_state = virtio_gpu_plane_duplicate_state,
> .atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
> };
>
> @@ -139,11 +156,13 @@ static void virtio_gpu_resource_flush(struct
> drm_plane *plane,
> struct drm_device *dev = plane->dev;
> struct virtio_gpu_device *vgdev = dev->dev_private;
> struct virtio_gpu_framebuffer *vgfb;
> + struct virtio_gpu_plane_state *vgplane_st;
> struct virtio_gpu_object *bo;
>
> vgfb = to_virtio_gpu_framebuffer(plane->state->fb);
> + vgplane_st = to_virtio_gpu_plane_state(plane->state);
> bo = gem_to_virtio_gpu_obj(vgfb->base.obj[0]);
> - if (vgfb->fence) {
> + if (vgplane_st->fence) {
> struct virtio_gpu_object_array *objs;
>
> objs = virtio_gpu_array_alloc(1);
> @@ -152,13 +171,11 @@ static void virtio_gpu_resource_flush(struct
> drm_plane *plane,
> virtio_gpu_array_add_obj(objs, vgfb->base.obj[0]);
> virtio_gpu_array_lock_resv(objs);
> virtio_gpu_cmd_resource_flush(vgdev, bo->hw_res_handle,
> x, y,
> - width, height, objs, vgfb->fence);
> + width, height, objs,
> + vgplane_st->fence);
> virtio_gpu_notify(vgdev);
> -
> - dma_fence_wait_timeout(&vgfb->fence->f, true,
> + dma_fence_wait_timeout(&vgplane_st->fence->f, true,
> msecs_to_jiffies(50));
> - dma_fence_put(&vgfb->fence->f);
> - vgfb->fence = NULL;
Not sure if it makes any difference but would there be a problem if you unref
the fence here (existing behavior) instead of deferring it until cleanup?
> } else {
> virtio_gpu_cmd_resource_flush(vgdev, bo->hw_res_handle,
> x, y,
> width, height, NULL, NULL);
> @@ -248,12 +265,14 @@ static int virtio_gpu_plane_prepare_fb(struct
> drm_plane *plane,
> struct drm_device *dev = plane->dev;
> struct virtio_gpu_device *vgdev = dev->dev_private;
> struct virtio_gpu_framebuffer *vgfb;
> + struct virtio_gpu_plane_state *vgplane_st;
> struct virtio_gpu_object *bo;
>
> if (!new_state->fb)
> return 0;
>
> vgfb = to_virtio_gpu_framebuffer(new_state->fb);
> + vgplane_st = to_virtio_gpu_plane_state(new_state);
> bo = gem_to_virtio_gpu_obj(vgfb->base.obj[0]);
>
> drm_gem_plane_helper_prepare_fb(plane, new_state);
> @@ -261,10 +280,11 @@ static int virtio_gpu_plane_prepare_fb(struct
> drm_plane *plane,
> if (!bo || (plane->type == DRM_PLANE_TYPE_PRIMARY && !bo-
> >guest_blob))
> return 0;
>
> - if (bo->dumb && (plane->state->fb != new_state->fb)) {
> - vgfb->fence = virtio_gpu_fence_alloc(vgdev, vgdev-
> >fence_drv.context,
> + if (bo->dumb) {
> + vgplane_st->fence = virtio_gpu_fence_alloc(vgdev,
> + vgdev->fence_drv.context,
> 0);
> - if (!vgfb->fence)
> + if (!vgplane_st->fence)
> return -ENOMEM;
> }
>
> @@ -274,15 +294,15 @@ static int virtio_gpu_plane_prepare_fb(struct
> drm_plane *plane,
> static void virtio_gpu_plane_cleanup_fb(struct drm_plane *plane,
> struct drm_plane_state *state)
> {
> - struct virtio_gpu_framebuffer *vgfb;
> + struct virtio_gpu_plane_state *vgplane_st;
>
> if (!state->fb)
> return;
>
> - vgfb = to_virtio_gpu_framebuffer(state->fb);
> - if (vgfb->fence) {
> - dma_fence_put(&vgfb->fence->f);
> - vgfb->fence = NULL;
> + vgplane_st = to_virtio_gpu_plane_state(state);
> + if (vgplane_st->fence) {
> + dma_fence_put(&vgplane_st->fence->f);
> + vgplane_st->fence = NULL;
> }
> }
>
> @@ -295,6 +315,7 @@ static void virtio_gpu_cursor_plane_update(struct
> drm_plane *plane,
> struct virtio_gpu_device *vgdev = dev->dev_private;
> struct virtio_gpu_output *output = NULL;
> struct virtio_gpu_framebuffer *vgfb;
> + struct virtio_gpu_plane_state *vgplane_st;
> struct virtio_gpu_object *bo = NULL;
> uint32_t handle;
>
> @@ -307,6 +328,7 @@ static void virtio_gpu_cursor_plane_update(struct
> drm_plane *plane,
>
> if (plane->state->fb) {
> vgfb = to_virtio_gpu_framebuffer(plane->state->fb);
> + vgplane_st = to_virtio_gpu_plane_state(plane->state);
> bo = gem_to_virtio_gpu_obj(vgfb->base.obj[0]);
> handle = bo->hw_res_handle;
> } else {
> @@ -326,11 +348,9 @@ static void virtio_gpu_cursor_plane_update(struct
> drm_plane *plane,
> (vgdev, 0,
> plane->state->crtc_w,
> plane->state->crtc_h,
> - 0, 0, objs, vgfb->fence);
> + 0, 0, objs, vgplane_st->fence);
> virtio_gpu_notify(vgdev);
> - dma_fence_wait(&vgfb->fence->f, true);
> - dma_fence_put(&vgfb->fence->f);
> - vgfb->fence = NULL;
Same comment as above.
Regardless, the patch LGTM.
Acked-by: Vivek Kasireddy <vivek.kasire...@intel.com>
> + dma_fence_wait(&vgplane_st->fence->f, true);
> }
>
> if (plane->state->fb != old_state->fb) {
> --
> 2.47.0
