[Intel-gfx] [PATCH 32/32] drm/i915: Flush the RPS bottom-half when the GPU idles

[Chris Wilson]

Make sure that the RPS bottom-half is flushed before we set the idle
frequency when we decide the GPU is idle. This should prevent any races
with the bottom-half and setting the idle frequency, and ensures that
the bottom-half is bounded by the GPU's rpm reference taken for when it
is active (i.e. between gen6_rps_busy() and gen6_rps_idle()).

v2: Avoid recursively using the i915->wq - RPS does not touch the
struct_mutex so has no place being on the ordered i915->wq.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Imre Deak <imre.deak at intel.com>
Cc: Jesse Barnes <jbarnes at virtuousgeek.org>
---
 drivers/gpu/drm/i915/i915_irq.c |  2 +-
 drivers/gpu/drm/i915/intel_pm.c | 10 +++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index e5e307654c66..4cfbd694b3a8 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1609,7 +1609,7 @@ static void gen6_rps_irq_handler(struct drm_i915_private *dev_priv, u32 pm_iir)
 		gen6_disable_pm_irq(dev_priv, pm_iir & dev_priv->pm_rps_events);
 		if (dev_priv->rps.interrupts_enabled) {
 			dev_priv->rps.pm_iir |= pm_iir & dev_priv->pm_rps_events;
-			queue_work(dev_priv->wq, &dev_priv->rps.work);
+			schedule_work(&dev_priv->rps.work);
 		}
 		spin_unlock(&dev_priv->irq_lock);
 	}
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 570628628a90..f543f897c516 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4401,11 +4401,15 @@ void gen6_rps_busy(struct drm_i915_private *dev_priv)
 
 void gen6_rps_idle(struct drm_i915_private *dev_priv)
 {
-	struct drm_device *dev = dev_priv->dev;
+	/* Flush our bottom-half so that it does not race with us
+	 * setting the idle frequency and so that it is bounded by
+	 * our rpm wakeref.
+	 */
+	flush_work(&dev_priv->rps.work);
 
 	mutex_lock(&dev_priv->rps.hw_lock);
 	if (dev_priv->rps.enabled) {
-		if (IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev))
+		if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
 			vlv_set_rps_idle(dev_priv);
 		else
 			gen6_set_rps(dev_priv->dev, dev_priv->rps.idle_freq);
@@ -4443,7 +4447,7 @@ void gen6_rps_boost(struct drm_i915_private *dev_priv,
 		spin_lock_irq(&dev_priv->irq_lock);
 		if (dev_priv->rps.interrupts_enabled) {
 			dev_priv->rps.client_boost = true;
-			queue_work(dev_priv->wq, &dev_priv->rps.work);
+			schedule_work(&dev_priv->rps.work);
 		}
 		spin_unlock_irq(&dev_priv->irq_lock);
 
-- 
2.6.3