drm/i915: Track GT wakeref

Record the wakeref used for keeping the device awake as the GPU is
executing requests and be sure to cancel the tracking upon parking.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-3-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_drv.h

@@ -1979,7 +1979,7 @@ struct drm_i915_private {
 		 * In order to reduce the effect on performance, there
 		 * is a slight delay before we do so.
 		 */
-		bool awake;
+		intel_wakeref_t awake;
 
 		/**
 		 * The number of times we have woken up.

drivers/gpu/drm/i915/i915_gem.c

@@ -138,6 +138,8 @@ int i915_mutex_lock_interruptible(struct drm_device *dev)
 
 static u32 __i915_gem_park(struct drm_i915_private *i915)
 {
+	intel_wakeref_t wakeref;
+
 	GEM_TRACE("\n");
 
 	lockdep_assert_held(&i915->drm.struct_mutex);
@@ -168,14 +170,15 @@ static u32 __i915_gem_park(struct drm_i915_private *i915)
 	i915_pmu_gt_parked(i915);
 	i915_vma_parked(i915);
 
-	i915->gt.awake = false;
+	wakeref = fetch_and_zero(&i915->gt.awake);
+	GEM_BUG_ON(!wakeref);
 
 	if (INTEL_GEN(i915) >= 6)
 		gen6_rps_idle(i915);
 
 	intel_display_power_put(i915, POWER_DOMAIN_GT_IRQ);
 
-	intel_runtime_pm_put_unchecked(i915);
+	intel_runtime_pm_put(i915, wakeref);
 
 	return i915->gt.epoch;
 }
@@ -204,7 +207,8 @@ void i915_gem_unpark(struct drm_i915_private *i915)
 	if (i915->gt.awake)
 		return;
 
-	intel_runtime_pm_get_noresume(i915);
+	i915->gt.awake = intel_runtime_pm_get_noresume(i915);
+	GEM_BUG_ON(!i915->gt.awake);
 
 	/*
 	 * It seems that the DMC likes to transition between the DC states a lot
@@ -219,7 +223,6 @@ void i915_gem_unpark(struct drm_i915_private *i915)
 	 */
 	intel_display_power_get(i915, POWER_DOMAIN_GT_IRQ);
 
-	i915->gt.awake = true;
 	if (unlikely(++i915->gt.epoch == 0)) /* keep 0 as invalid */
 		i915->gt.epoch = 1;