[Intel-gfx] [PATCH 6/7] drm/i915: Add a wakeref getter for iff the wakeref is already active

[Chris Wilson]

For use in the next patch, we want to acquire a wakeref without having
to wake the device up -- i.e. only acquire the engine wakeref if the
engine is already active.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/intel_engine_pm.h |  9 ++++++++-
 drivers/gpu/drm/i915/intel_wakeref.h      | 15 +++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.h b/drivers/gpu/drm/i915/gt/intel_engine_pm.h
index b326cd993d60..b4f72de3e1f9 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.h
@@ -7,12 +7,19 @@
 #ifndef INTEL_ENGINE_PM_H
 #define INTEL_ENGINE_PM_H
 
+#include "intel_engine_types.h"
+#include "intel_wakeref.h"
+
 struct drm_i915_private;
-struct intel_engine_cs;
 
 void intel_engine_pm_get(struct intel_engine_cs *engine);
 void intel_engine_pm_put(struct intel_engine_cs *engine);
 
+static inline bool intel_engine_pm_get_if_awake(struct intel_engine_cs *engine)
+{
+	return intel_wakeref_get_if_active(&engine->wakeref);
+}
+
 void intel_engine_park(struct intel_engine_cs *engine);
 
 void intel_engine_init__pm(struct intel_engine_cs *engine);
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
index f74272770a5c..1d6f5986e4e5 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.h
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -71,6 +71,21 @@ intel_wakeref_get(struct intel_runtime_pm *rpm,
 	return 0;
 }
 
+/**
+ * intel_wakeref_get_if_in_use: Acquire the wakeref
+ * @wf: the wakeref
+ *
+ * Acquire a hold on the wakeref, but only if the wakeref is already
+ * active.
+ *
+ * Returns: true if the wakeref was acquired, false otherwise.
+ */
+static inline bool
+intel_wakeref_get_if_active(struct intel_wakeref *wf)
+{
+	return atomic_inc_not_zero(&wf->count);
+}
+
 /**
  * intel_wakeref_put: Release the wakeref
  * @i915: the drm_i915_private device
-- 
2.20.1