drm/i915: Flush the RPS bottom-half when the GPU idles
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.
v3: Enable/disable interrupts for RPS busy/idle in order to prevent
further HW access from RPS outside of the wakeref.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
References: https://bugs.freedesktop.org/show_bug.cgi?id=89728
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467616119-4093-6-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 48e21c7..814b0df 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4864,6 +4864,8 @@
I915_WRITE(GEN6_PMINTRMSK,
gen6_rps_pm_mask(dev_priv, dev_priv->rps.cur_freq));
+ gen6_enable_rps_interrupts(dev_priv);
+
/* Ensure we start at the user's desired frequency */
intel_set_rps(dev_priv,
clamp(dev_priv->rps.cur_freq,
@@ -4875,6 +4877,13 @@
void gen6_rps_idle(struct drm_i915_private *dev_priv)
{
+ /* 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. And then disable the interrupts to stop any
+ * futher RPS reclocking whilst we are asleep.
+ */
+ gen6_disable_rps_interrupts(dev_priv);
+
mutex_lock(&dev_priv->rps.hw_lock);
if (dev_priv->rps.enabled) {
if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
@@ -4915,7 +4924,7 @@
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);