[Intel-gfx] [PATCH 03/10] 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

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 |  5 +++++
 drivers/gpu/drm/i915/intel_drv.h     |  3 +++
 drivers/gpu/drm/i915/intel_pm.c      | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index bbc3d509bcd7..455cb0b0dcac 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9761,6 +9761,10 @@ void intel_check_page_flip(struct drm_device *dev, int pipe)
 			 intel_crtc->unpin_work->flip_queued_vblank, drm_vblank_count(dev, pipe));
 		page_flip_completed(intel_crtc);
 	}
+	if (intel_crtc->unpin_work != NULL &&
+	    intel_crtc->unpin_work->rcs_active &&
+	    drm_vblank_count(dev, pipe) - intel_crtc->unpin_work->flip_queued_vblank > 1)
+		intel_queue_rps_boost_for_request(dev, intel_crtc->unpin_work->flip_queued_request);
 	spin_unlock_irqrestore(&dev->event_lock, flags);
 }
 
@@ -9856,6 +9860,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 	crtc->primary->fb = fb;
 
 	work->pending_flip_obj = obj;
+	work->rcs_active = RCS_ENGINE(dev_priv)->last_request != NULL;
 
 	atomic_inc(&intel_crtc->unpin_work_count);
 	intel_crtc->reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 1722673c534e..bbd59dd7be1b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -666,6 +666,7 @@ struct intel_unpin_work {
 	int flip_queued_vblank;
 	int flip_ready_vblank;
 	bool enable_stall_check;
+	bool rcs_active;
 };
 
 struct intel_set_config {
@@ -1076,6 +1077,8 @@ void ironlake_teardown_rc6(struct drm_device *dev);
 void gen6_update_ring_freq(struct drm_device *dev);
 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 i915_gem_request *rq);
 void intel_aux_display_runtime_get(struct drm_i915_private *dev_priv);
 void intel_aux_display_runtime_put(struct drm_i915_private *dev_priv);
 void intel_runtime_pm_get(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 2f4e38f36523..a560eb109160 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -7568,6 +7568,40 @@ int vlv_freq_opcode(struct drm_i915_private *dev_priv, int val)
 	return ret;
 }
 
+struct request_boost {
+	struct work_struct work;
+	struct 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_request_complete(boost->rq))
+		gen6_rps_boost(boost->rq->i915);
+
+	i915_request_put__unlocked(boost->rq);
+	kfree(boost);
+}
+
+void intel_queue_rps_boost_for_request(struct drm_device *dev,
+				       struct 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);
+	boost->rq = i915_request_get(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;
-- 
2.1.0