[Intel-gfx] [PATCH v2 38/39] drm/i915: add descriptions for some RPM macros at intel_gt_pm.h

[Mauro Carvalho Chehab]

The intel_gt_pm.h file contains some convenient macros to be used
in GT code in order to get/put runtime PM references and for
checking them.

Add descriptions based on the ones at intel_wakeref.h and
intel_runtime_pm.c.

Signed-off-by: Mauro Carvalho Chehab <mchehab at kernel.org>
---

To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
See [PATCH v2 00/39] at: https://lore.kernel.org/all/cover.1657699522.git.mchehab@kernel.org/

 Documentation/gpu/i915.rst            |  2 +
 drivers/gpu/drm/i915/gt/intel_gt_pm.h | 62 +++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst
index 6bb50edc6d79..9862d504df4d 100644
--- a/Documentation/gpu/i915.rst
+++ b/Documentation/gpu/i915.rst
@@ -709,6 +709,8 @@ Table Manager (TTM)
 
 .. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
 
+.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_gt_pm.h
+
 Graphics Execution Manager (GEM)
 --------------------------------
 
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
index bc898df7a48c..a8ea6846980a 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
@@ -11,21 +11,57 @@
 #include "intel_gt_types.h"
 #include "intel_wakeref.h"
 
+/**
+ * intel_gt_pm_is_awake: Query whether the runtime PM is awake held
+ *
+ * @gt: pointer to the graphics engine
+ *
+ * Returns: true if a runtime pm reference is currently held and the GT is
+ * awake.
+ */
 static inline bool intel_gt_pm_is_awake(const struct intel_gt *gt)
 {
 	return intel_wakeref_is_active(&gt->wakeref);
 }
 
+/**
+ * intel_gt_pm_get: grab a runtime PM reference ensuring that GT is powered up
+ * @gt: pointer to the graphics engine
+ *
+ * Any runtime pm reference obtained by this function must have a symmetric
+ * call to intel_gt_pm_put() to release the reference again.
+ *
+ * Note that this is allowed to fail, in which case the runtime-pm wakeref
+ * will be released and the acquisition unwound.
+ */
 static inline void intel_gt_pm_get(struct intel_gt *gt)
 {
 	intel_wakeref_get(&gt->wakeref);
 }
 
+/**
+ * __intel_gt_pm_get: Acquire the runtime PM reference again
+ * @gt: pointer to the graphics engine which contains the wakeref
+ *
+ * Increment the PM reference counter, only valid if it is already held by
+ * the caller.
+ *
+ * See intel_gt_pm_get().
+ */
 static inline void __intel_gt_pm_get(struct intel_gt *gt)
 {
 	__intel_wakeref_get(&gt->wakeref);
 }
 
+/**
+ * intel_gt_pm_get_if_awake: Acquire the runtime PM reference if active
+ * @gt: pointer to the graphics engine which contains the PM reference
+ *
+ * Acquire a hold on the PM reference, but only if the GT is already
+ * active.
+ *
+ * Returns: true if the wakeref was acquired, false otherwise.
+ */
 static inline bool intel_gt_pm_get_if_awake(struct intel_gt *gt)
 {
 	return intel_wakeref_get_if_active(&gt->wakeref);
@@ -36,6 +72,14 @@ static inline void intel_gt_pm_might_get(struct intel_gt *gt)
 	intel_wakeref_might_get(&gt->wakeref);
 }
 
+/**
+ * intel_gt_pm_put: Release the runtime PM reference
+ * @gt: pointer to the graphics engine which contains the PM reference
+ *
+ * Release our hold on the runtime PM for GT.
+ *
+ * It might power down the GT right away if this is the last reference.
+ */
 static inline void intel_gt_pm_put(struct intel_gt *gt)
 {
 	intel_wakeref_put(&gt->wakeref);
@@ -51,10 +95,28 @@ static inline void intel_gt_pm_might_put(struct intel_gt *gt)
 	intel_wakeref_might_put(&gt->wakeref);
 }
 
+/**
+ * with_intel_gt_pm - get a GT reference ensuring that GT is powered up,
+ *	run some code and then put the reference away.
+ *
+ * @gt: pointer to the gt
+ * @tmp: pointer to a temporary wakeref.
+ */
 #define with_intel_gt_pm(gt, tmp) \
 	for (tmp = 1, intel_gt_pm_get(gt); tmp; \
 	     intel_gt_pm_put(gt), tmp = 0)
 
+/**
+ * intel_gt_pm_wait_for_idle: Wait until the runtime PM reference is idle
+ * @gt: pointer to the graphics engine which contains the PM reference
+ *
+ * Wait for the earlier asynchronous release of the runtime PM reference. Note
+ * this will wait for any third party as well, so make sure you only wait
+ * when you have control over the GT runtime PM and trust no one else is
+ * acquiring it.
+ *
+ * Return: 0 on success, error code if killed.
+ */
 static inline int intel_gt_pm_wait_for_idle(struct intel_gt *gt)
 {
 	return intel_wakeref_wait_for_idle(&gt->wakeref);
-- 
2.36.1