[PATCH v2 2/5] drm/virtio: Disable damage clipping if FB changed since last page-flip

[Javier Martinez Canillas <javierm@redhat.com>]

The driver does per-buffer uploads and needs to force a full plane update
if the plane's attached framebuffer has change since the last page-flip.

Fixes: 01f05940a9a7 ("drm/virtio: Enable fb damage clips property for the primary plane")
Cc: <stable@vger.kernel.org> # v6.4+
Reported-by: nerdopolis <bluescreen_avenger@verizon.net>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218115
Suggested-by: Sima Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

Changes in v2:
- Set struct drm_plane_state .ignore_damage_clips in virtio-gpu plane's
  .atomic_check instead of using a different helpers (Thomas Zimmermann).

 drivers/gpu/drm/virtio/virtgpu_plane.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index a2e045f3a000..a1ef657eba07 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -79,6 +79,8 @@ static int virtio_gpu_plane_atomic_check(struct drm_plane *plane,
 {
 	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
 										 plane);
+	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state,
+										 plane);
 	bool is_cursor = plane->type == DRM_PLANE_TYPE_CURSOR;
 	struct drm_crtc_state *crtc_state;
 	int ret;
@@ -86,6 +88,14 @@ static int virtio_gpu_plane_atomic_check(struct drm_plane *plane,
 	if (!new_plane_state->fb || WARN_ON(!new_plane_state->crtc))
 		return 0;
 
+	/*
+	 * Ignore damage clips if the framebuffer attached to the plane's state
+	 * has changed since the last plane update (page-flip). In this case, a
+	 * full plane update should happen because uploads are done per-buffer.
+	 */
+	if (old_plane_state->fb != new_plane_state->fb)
+		new_plane_state->ignore_damage_clips = true;
+
 	crtc_state = drm_atomic_get_crtc_state(state,
 					       new_plane_state->crtc);
 	if (IS_ERR(crtc_state))
-- 
2.41.0