drm/i915: Free RPS boosts for all laggards

If the client stalls on a congested request, chosen to be 20ms old to
match throttling, allow the client a free RPS boost.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: s/rq/req/]
[danvet: s/0/NULL/ reported by 0-day build]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -1245,7 +1245,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
 		jiffies + nsecs_to_jiffies_timeout((u64)*timeout) : 0;
 
 	if (INTEL_INFO(dev_priv)->gen >= 6)
-		gen6_rps_boost(dev_priv, rps);
+		gen6_rps_boost(dev_priv, rps, req->emitted_jiffies);
 
 	/* Record current time in case interrupted by signal, or wedged */
 	trace_i915_gem_request_wait_begin(req);

drivers/gpu/drm/i915/intel_drv.h

@@ -1365,7 +1365,8 @@ 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,
-		    struct intel_rps_client *rps);
+		    struct intel_rps_client *rps,
+		    unsigned long submitted);
 void intel_queue_rps_boost_for_request(struct drm_device *dev,
 				       struct drm_i915_gem_request *req);
 void ilk_wm_get_hw_state(struct drm_device *dev);

drivers/gpu/drm/i915/intel_pm.c

@@ -4150,10 +4150,17 @@ void gen6_rps_idle(struct drm_i915_private *dev_priv)
 }
 
 void gen6_rps_boost(struct drm_i915_private *dev_priv,
-		    struct intel_rps_client *rps)
+		    struct intel_rps_client *rps,
+		    unsigned long submitted)
 {
 	u32 val;
 
+	/* Force a RPS boost (and don't count it against the client) if
+	 * the GPU is severely congested.
+	 */
+	if (rps && time_after(jiffies, submitted + msecs_to_jiffies(20)))
+		rps = NULL;
+
 	mutex_lock(&dev_priv->rps.hw_lock);
 	val = dev_priv->rps.max_freq_softlimit;
 	if (dev_priv->rps.enabled &&
@@ -6848,11 +6855,13 @@ struct request_boost {
 static void __intel_rps_boost_work(struct work_struct *work)
 {
 	struct request_boost *boost = container_of(work, struct request_boost, work);
+	struct drm_i915_gem_request *req = boost->req;
 
-	if (!i915_gem_request_completed(boost->req, true))
-		gen6_rps_boost(to_i915(boost->req->ring->dev), NULL);
+	if (!i915_gem_request_completed(req, true))
+		gen6_rps_boost(to_i915(req->ring->dev), NULL,
+			       req->emitted_jiffies);
 
-	i915_gem_request_unreference__unlocked(boost->req);
+	i915_gem_request_unreference__unlocked(req);
 	kfree(boost);
 }
 
@@ -6864,6 +6873,9 @@ void intel_queue_rps_boost_for_request(struct drm_device *dev,
 	if (req == NULL || INTEL_INFO(dev)->gen < 6)
 		return;
 
+	if (i915_gem_request_completed(req, true))
+		return;
+
 	boost = kmalloc(sizeof(*boost), GFP_ATOMIC);
 	if (boost == NULL)
 		return;