3 files changed, 22 insertions, 16 deletions

diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c
index e66ff25c008e..e9fb4ebb789f 100644
--- a/drivers/gpu/drm/vkms/vkms_crc.c
+++ b/drivers/gpu/drm/vkms/vkms_crc.c
@@ -166,16 +166,24 @@ void vkms_crc_work_handle(struct work_struct *work)
 	struct drm_plane *plane;
 	u32 crc32 = 0;
 	u64 frame_start, frame_end;
+	bool crc_pending;
 	unsigned long flags;
 
 	spin_lock_irqsave(&out->state_lock, flags);
 	frame_start = crtc_state->frame_start;
 	frame_end = crtc_state->frame_end;
+	crc_pending = crtc_state->crc_pending;
+	crtc_state->frame_start = 0;
+	crtc_state->frame_end = 0;
+	crtc_state->crc_pending = false;
 	spin_unlock_irqrestore(&out->state_lock, flags);
 
-	/* _vblank_handle() hasn't updated frame_start yet */
-	if (!frame_start || frame_start == frame_end)
-		goto out;
+	/*
+	 * We raced with the vblank hrtimer and previous work already computed
+	 * the crc, nothing to do.
+	 */
+	if (!crc_pending)
+		return;
 
 	drm_for_each_plane(plane, &vdev->drm) {
 		struct vkms_plane_state *vplane_state;
@@ -196,20 +204,11 @@ void vkms_crc_work_handle(struct work_struct *work)
 	if (primary_crc)
 		crc32 = _vkms_get_crc(primary_crc, cursor_crc);
 
-	frame_end = drm_crtc_accurate_vblank_count(crtc);
-
-	/* queue_work can fail to schedule crc_work; add crc for
-	 * missing frames
+	/*
+	 * The worker can fall behind the vblank hrtimer, make sure we catch up.
 	 */
 	while (frame_start <= frame_end)
 		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
-
-out:
-	/* to avoid using the same value for frame number again */
-	spin_lock_irqsave(&out->state_lock, flags);
-	crtc_state->frame_end = frame_end;
-	crtc_state->frame_start = 0;
-	spin_unlock_irqrestore(&out->state_lock, flags);
 }
 
 static const char * const pipe_crc_sources[] = {"auto"};
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 4d11292bc6f3..f392fa13015b 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -30,13 +30,18 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
 		 * has read the data
 		 */
 		spin_lock(&output->state_lock);
-		if (!state->frame_start)
+		if (!state->crc_pending)
 			state->frame_start = frame;
+		else
+			DRM_DEBUG_DRIVER("crc worker falling behind, frame_start: %llu, frame_end: %llu\n",
+					 state->frame_start, frame);
+		state->frame_end = frame;
+		state->crc_pending = true;
 		spin_unlock(&output->state_lock);
 
 		ret = queue_work(output->crc_workq, &state->crc_work);
 		if (!ret)
-			DRM_WARN("failed to queue vkms_crc_work_handle");
+			DRM_DEBUG_DRIVER("vkms_crc_work_handle already queued\n");
 	}
 
 	spin_unlock(&output->lock);
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index b92c30c66a6f..2b37eb1062d3 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -48,6 +48,8 @@ struct vkms_plane_state {
 struct vkms_crtc_state {
 	struct drm_crtc_state base;
 	struct work_struct crc_work;
+
+	bool crc_pending;
 	u64 frame_start;
 	u64 frame_end;
 };