drm/i915/guc: Grab RPM wakelock while disabling GuC interrupts

Disabling GuC interrupts involves access to GuC IRQ control registers
hence ensure device is RPM awake.

v1-v2: old changelog
1: Add comment about need to synchronize flush work and log runtime
   destroy
2: Moved patch earlier in the series and removed comment about future
work. (Tvrtko)

v3: Added assert_rpm_wakelock_held() to gen9_*_guc_interrupts. (Chris)
Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/1516808821-3638-1-git-send-email-sagar.a.kamble@intel.com

drivers/gpu/drm/i915/i915_irq.c

@@ -452,6 +452,8 @@ void gen6_disable_rps_interrupts(struct drm_i915_private *dev_priv)
 
 void gen9_reset_guc_interrupts(struct drm_i915_private *dev_priv)
 {
+	assert_rpm_wakelock_held(dev_priv);
+
 	spin_lock_irq(&dev_priv->irq_lock);
 	gen6_reset_pm_iir(dev_priv, dev_priv->pm_guc_events);
 	spin_unlock_irq(&dev_priv->irq_lock);
@@ -459,6 +461,8 @@ void gen9_reset_guc_interrupts(struct drm_i915_private *dev_priv)
 
 void gen9_enable_guc_interrupts(struct drm_i915_private *dev_priv)
 {
+	assert_rpm_wakelock_held(dev_priv);
+
 	spin_lock_irq(&dev_priv->irq_lock);
 	if (!dev_priv->guc.interrupts_enabled) {
 		WARN_ON_ONCE(I915_READ(gen6_pm_iir(dev_priv)) &
@@ -471,6 +475,8 @@ void gen9_enable_guc_interrupts(struct drm_i915_private *dev_priv)
 
 void gen9_disable_guc_interrupts(struct drm_i915_private *dev_priv)
 {
+	assert_rpm_wakelock_held(dev_priv);
+
 	spin_lock_irq(&dev_priv->irq_lock);
 	dev_priv->guc.interrupts_enabled = false;
 

drivers/gpu/drm/i915/intel_guc_log.c

@@ -639,7 +639,10 @@ void i915_guc_log_unregister(struct drm_i915_private *dev_priv)
 
 	mutex_lock(&dev_priv->drm.struct_mutex);
 	/* GuC logging is currently the only user of Guc2Host interrupts */
+	intel_runtime_pm_get(dev_priv);
 	gen9_disable_guc_interrupts(dev_priv);
+	intel_runtime_pm_put(dev_priv);
+
 	guc_log_runtime_destroy(&dev_priv->guc);
 	mutex_unlock(&dev_priv->drm.struct_mutex);
 }