[Intel-gfx] [PATCH 6/7] drm/i915: Boost GPU frequency if we detect outstanding pageflips

[Chris Wilson]

If we hit a vblank and see that have a pageflip queue but not yet
processed, ensure that the GPU is running at maximum in order to clear
the backlog. Pageflips are only queued for the following vblank, if we
miss it, there will be a visible stutter. Boosting the GPU frequency
doesn't prevent us from missing the target vblank, but it should help
the subsequent frames hitting theirs.

v2: Reorder vblank vs flip-complete so that we only check for a missed
flip after processing the completion events, and avoid spurious boosts.

v3: Rename missed_vblank
v4: Rebase
v5: Cancel the outstanding work in runtime suspend
v6: Rebase

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 11 ++++++++---
 drivers/gpu/drm/i915/intel_drv.h     |  2 ++
 drivers/gpu/drm/i915/intel_pm.c      | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2412002d510b..7735f0a4184c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9818,6 +9818,7 @@ void intel_check_page_flip(struct drm_device *dev, int pipe)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	struct intel_unpin_work *work;
 
 	WARN_ON(!in_irq());
 
@@ -9825,12 +9826,16 @@ void intel_check_page_flip(struct drm_device *dev, int pipe)
 		return;
 
 	spin_lock(&dev->event_lock);
-	if (intel_crtc->unpin_work && __intel_pageflip_stall_check(dev, crtc)) {
+	work = intel_crtc->unpin_work;
+	if (work != NULL && __intel_pageflip_stall_check(dev, crtc)) {
 		WARN_ONCE(1, "Kicking stuck page flip: queued at %d, now %d\n",
-			 intel_crtc->unpin_work->flip_queued_vblank,
-			 drm_vblank_count(dev, pipe));
+			 work->flip_queued_vblank, drm_vblank_count(dev, pipe));
 		page_flip_completed(intel_crtc);
+		work = NULL;
 	}
+	if (work != NULL &&
+	    drm_vblank_count(dev, pipe) - work->flip_queued_vblank > 1)
+		intel_queue_rps_boost_for_request(dev, work->flip_queued_req);
 	spin_unlock(&dev->event_lock);
 }
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 1e564da2fd38..87e09a58191a 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1242,6 +1242,8 @@ void gen6_rps_busy(struct drm_i915_private *dev_priv);
 void gen6_rps_reset_ei(struct drm_i915_private *dev_priv);
 void gen6_rps_idle(struct drm_i915_private *dev_priv);
 void gen6_rps_boost(struct drm_i915_private *dev_priv);
+void intel_queue_rps_boost_for_request(struct drm_device *dev,
+				       struct drm_i915_gem_request *rq);
 void ilk_wm_get_hw_state(struct drm_device *dev);
 void skl_wm_get_hw_state(struct drm_device *dev);
 void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv,
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 972333d2211d..120b8af3c60c 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6598,6 +6598,40 @@ int intel_freq_opcode(struct drm_i915_private *dev_priv, int val)
 		return val / GT_FREQUENCY_MULTIPLIER;
 }
 
+struct request_boost {
+	struct work_struct work;
+	struct drm_i915_gem_request *rq;
+};
+
+static void __intel_rps_boost_work(struct work_struct *work)
+{
+	struct request_boost *boost = container_of(work, struct request_boost, work);
+
+	if (!i915_gem_request_completed(boost->rq, true))
+		gen6_rps_boost(to_i915(boost->rq->ring->dev));
+
+	i915_gem_request_unreference(boost->rq);
+	kfree(boost);
+}
+
+void intel_queue_rps_boost_for_request(struct drm_device *dev,
+				       struct drm_i915_gem_request *rq)
+{
+	struct request_boost *boost;
+
+	if (rq == NULL || INTEL_INFO(dev)->gen < 6)
+		return;
+
+	boost = kmalloc(sizeof(*boost), GFP_ATOMIC);
+	if (boost == NULL)
+		return;
+
+	INIT_WORK(&boost->work, __intel_rps_boost_work);
+	i915_gem_request_assign(&boost->rq, rq);
+
+	queue_work(to_i915(dev)->wq, &boost->work);
+}
+
 void intel_pm_setup(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-- 
2.1.4