[PATCH] drm/msm: enable vblank during atomic commits

From: Rob Clark <robdclark@gmail.com>
To: dri-devel@lists.freedesktop.org
Cc: Rob Clark <robdclark@chromium.org>,
	Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	linux-arm-msm@vger.kernel.org (open list:DRM DRIVER FOR MSM
	ADRENO GPU),
	freedreno@lists.freedesktop.org (open list:DRM DRIVER FOR MSM
	ADRENO GPU), linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] drm/msm: enable vblank during atomic commits
Date: Tue, 18 Aug 2020 09:31:19 -0700	[thread overview]
Message-ID: <20200818163119.715410-1-robdclark@gmail.com> (raw)

From: Rob Clark <robdclark@chromium.org>

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>
---
 drivers/gpu/drm/msm/msm_atomic.c | 36 ++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
index 5ccfad794c6a..561bfa48841c 100644
--- a/drivers/gpu/drm/msm/msm_atomic.c
+++ b/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);
-- 
2.26.2

