[Intel-gfx] [PATCH 2/2] drm/i915: Defer unmasking RPS interrupts until after making adjustments

[Chris Wilson]

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 <ch...@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 29b10bab38b6..0dfd434584aa 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1120,30 +1120,21 @@ 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);
 
@@ -1200,6 +1191,13 @@ 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);
 }
 
 
-- 
2.11.0

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