[PATCH v4 3/4] drm: Document variable refresh properties

[Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>]

These include the drm_connector 'vrr_capable' and the drm_crtc
'vrr_enabled' properties.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
---
 Documentation/gpu/drm-kms.rst   |  7 +++++++
 drivers/gpu/drm/drm_connector.c | 22 ++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst
index 4b1501b4835b..8da2a178cf85 100644
--- a/Documentation/gpu/drm-kms.rst
+++ b/Documentation/gpu/drm-kms.rst
@@ -575,6 +575,13 @@ Explicit Fencing Properties
 .. kernel-doc:: drivers/gpu/drm/drm_atomic_uapi.c
    :doc: explicit fencing properties
 
+
+Variable Refresh Properties
+---------------------------
+
+.. kernel-doc:: drivers/gpu/drm/drm_connector.c
+   :doc: Variable refresh properties
+
 Existing KMS Properties
 -----------------------
 
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index f0deeb7298d0..2a12853ca917 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1254,6 +1254,28 @@ int drm_mode_create_scaling_mode_property(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_mode_create_scaling_mode_property);
 
+/**
+ * DOC: Variable refresh properties
+ *
+ * Variable refresh rate control is supported via properties on the
+ * &drm_connector and &drm_crtc objects.
+ *
+ * "vrr_capable":
+ *	Optional &drm_connector boolean property that drivers should attach
+ *	with drm_connector_attach_vrr_capable_property() on connectors that
+ *	could support variable refresh rates. Drivers should update the
+ *	property value by calling drm_connector_set_vrr_capable_property().
+ *
+ *	Absence of the property should indicate absence of support.
+ *
+ * "vrr_enabled":
+ *	Default &drm_crtc boolean property that notifies the driver that the
+ *	variable refresh rate adjustment should be enabled for the CRTC.
+ *
+ *	Support for variable refresh rate will depend on the "vrr_capable"
+ *	property exposed on the &drm_connector object.
+ */
+
 /**
  * drm_connector_attach_vrr_capable_property - creates the
  * vrr_capable property
-- 
2.19.1

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