drm/msm: enable vblank during atomic commits

This has roughly the same effect as drm_atomic_helper_wait_for_vblanks(),
basically just ensuring that vblank accounting is enabled so that we get
valid timestamp/seqn on pageflip events.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Tested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_atomic.c

@@ -27,6 +27,34 @@ int msm_atomic_prepare_fb(struct drm_plane *plane,
 	return msm_framebuffer_prepare(new_state->fb, kms->aspace);
 }
 
+/*
+ * Helpers to control vblanks while we flush.. basically just to ensure
+ * that vblank accounting is switched on, so we get valid seqn/timestamp
+ * on pageflip events (if requested)
+ */
+
+static void vblank_get(struct msm_kms *kms, unsigned crtc_mask)
+{
+	struct drm_crtc *crtc;
+
+	for_each_crtc_mask(kms->dev, crtc, crtc_mask) {
+		if (!crtc->state->active)
+			continue;
+		drm_crtc_vblank_get(crtc);
+	}
+}
+
+static void vblank_put(struct msm_kms *kms, unsigned crtc_mask)
+{
+	struct drm_crtc *crtc;
+
+	for_each_crtc_mask(kms->dev, crtc, crtc_mask) {
+		if (!crtc->state->active)
+			continue;
+		drm_crtc_vblank_put(crtc);
+	}
+}
+
 static void msm_atomic_async_commit(struct msm_kms *kms, int crtc_idx)
 {
 	unsigned crtc_mask = BIT(crtc_idx);
@@ -44,6 +72,8 @@ static void msm_atomic_async_commit(struct msm_kms *kms, int crtc_idx)
 
 	kms->funcs->enable_commit(kms);
 
+	vblank_get(kms, crtc_mask);
+
 	/*
 	 * Flush hardware updates:
 	 */
@@ -58,6 +88,8 @@ static void msm_atomic_async_commit(struct msm_kms *kms, int crtc_idx)
 	kms->funcs->wait_flush(kms, crtc_mask);
 	trace_msm_atomic_wait_flush_finish(crtc_mask);
 
+	vblank_put(kms, crtc_mask);
+
 	mutex_lock(&kms->commit_lock);
 	kms->funcs->complete_commit(kms, crtc_mask);
 	mutex_unlock(&kms->commit_lock);
@@ -221,6 +253,8 @@ void msm_atomic_commit_tail(struct drm_atomic_state *state)
 	 */
 	kms->pending_crtc_mask &= ~crtc_mask;
 
+	vblank_get(kms, crtc_mask);
+
 	/*
 	 * Flush hardware updates:
 	 */
@@ -235,6 +269,8 @@ void msm_atomic_commit_tail(struct drm_atomic_state *state)
 	kms->funcs->wait_flush(kms, crtc_mask);
 	trace_msm_atomic_wait_flush_finish(crtc_mask);
 
+	vblank_put(kms, crtc_mask);
+
 	mutex_lock(&kms->commit_lock);
 	kms->funcs->complete_commit(kms, crtc_mask);
 	mutex_unlock(&kms->commit_lock);