drm/i915: Defer unmasking RPS interrupts until after making adjustments

To make our adjustments to RPS requires taking a mutex and potentially
sleeping for an unknown duration - until we have completed our
adjustments further RPS interrupts are immaterial (they are based on
stale thresholds) and we can safely ignore them.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170309211232.28878-3-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 4469cac..ce445bc 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1148,30 +1148,21 @@ static void gen6_pm_rps_work(struct work_struct *work)
 {
        struct drm_i915_private *dev_priv =
                container_of(work, struct drm_i915_private, rps.work);
-       bool client_boost;
+       bool client_boost = false;
        int new_delay, adj, min, max;
-       u32 pm_iir;
+       u32 pm_iir = 0;
 
        spin_lock_irq(&dev_priv->irq_lock);
-       /* Speed up work cancelation during disabling rps interrupts. */
-       if (!dev_priv->rps.interrupts_enabled) {
-               spin_unlock_irq(&dev_priv->irq_lock);
-               return;
+       if (dev_priv->rps.interrupts_enabled) {
+               pm_iir = fetch_and_zero(&dev_priv->rps.pm_iir);
+               client_boost = fetch_and_zero(&dev_priv->rps.client_boost);
        }
-
-       pm_iir = dev_priv->rps.pm_iir;
-       dev_priv->rps.pm_iir = 0;
-       /* Make sure not to corrupt PMIMR state used by ringbuffer on GEN6 */
-       gen6_unmask_pm_irq(dev_priv, dev_priv->pm_rps_events);
-       client_boost = dev_priv->rps.client_boost;
-       dev_priv->rps.client_boost = false;
        spin_unlock_irq(&dev_priv->irq_lock);
 
        /* Make sure we didn't queue anything we're not going to process. */
        WARN_ON(pm_iir & ~dev_priv->pm_rps_events);
-
        if ((pm_iir & dev_priv->pm_rps_events) == 0 && !client_boost)
-               return;
+               goto out;
 
        mutex_lock(&dev_priv->rps.hw_lock);
 
@@ -1228,6 +1219,13 @@ static void gen6_pm_rps_work(struct work_struct *work)
        }
 
        mutex_unlock(&dev_priv->rps.hw_lock);
+
+out:
+       /* Make sure not to corrupt PMIMR state used by ringbuffer on GEN6 */
+       spin_lock_irq(&dev_priv->irq_lock);
+       if (dev_priv->rps.interrupts_enabled)
+               gen6_unmask_pm_irq(dev_priv, dev_priv->pm_rps_events);
+       spin_unlock_irq(&dev_priv->irq_lock);
 }