[PATCH v4 24/27] drm: Add passive_vrr_capable property to connector

[Tomasz Pakuła]

Supplement to the passive_vrr_disabled crtc property

Drivers can add the property to a connector with
drm_connector_attach_passive_vrr_capable_property().
The value should be updated based on driver and hardware capability
by using drm_connector_set_passive_vrr_capable_property().

Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@xxxxxxxxx>
---
 drivers/gpu/drm/drm_connector.c | 73 +++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h     | 15 +++++++
 2 files changed, 88 insertions(+)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 272d6254ea47..5bb38b80e214 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -2346,6 +2346,16 @@ EXPORT_SYMBOL(drm_mode_create_scaling_mode_property);
  *
  *	Absence of the property should indicate absence of support.
  *
+ * "passive_vrr_capable":
+ *	Optional &drm_connector boolean property that drivers should attach
+ *	with drm_connector_attach_passive_vrr_capable_property() on
+ *	connectors that could support keeping variable refresh rate signalling
+ *	in fixed-refresh rate scenarios like desktop work. Drivers should update
+ *	the property value by calling
+ *	drm_connector_set_passive_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
  *	content on the CRTC is suitable for variable refresh rate presentation.
@@ -2364,6 +2374,17 @@ EXPORT_SYMBOL(drm_mode_create_scaling_mode_property);
  *
  *	The driver may place further restrictions within these minimum
  *	and maximum bounds.
+ *
+ * "PASSIVE_VRR_DISABLED":
+ *	Default &drm_crtc boolean property that notifies the driver that the
+ *	VRR singalling should be disabled in fixed refresh rate scenarios.
+ *	Functionally, psssive vrr works the same as VRR_ENABLED == false
+ *	but works around displays blanking (mainly HDMI) that do not support
+ *	seamless VRR transitions. Also helps with brightness flickering during
+ *	VRR transitions.
+ *
+ *	Passive VRR mode is not that useful for DP/eDP sinks where seamless VRR
+ *	transitions are enforced by the standard.
  */
 
 /**
@@ -2397,6 +2418,37 @@ int drm_connector_attach_vrr_capable_property(
 }
 EXPORT_SYMBOL(drm_connector_attach_vrr_capable_property);
 
+/**
+ * drm_connector_attach_passive_vrr_capable_property - creates the
+ * passive_vrr_capable property
+ * @connector: connector to create the passive_vrr_capable property on.
+ *
+ * This is used by atomic drivers to add support for querying
+ * variable refresh rate on desktop capability for a connector.
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
+ */
+int drm_connector_attach_passive_vrr_capable_property(
+	struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_property *prop;
+
+	if (!connector->passive_vrr_capable_property) {
+		prop = drm_property_create_bool(dev, DRM_MODE_PROP_IMMUTABLE,
+			"passive_vrr_capable");
+		if (!prop)
+			return -ENOMEM;
+
+		connector->passive_vrr_capable_property = prop;
+		drm_object_attach_property(&connector->base, prop, 0);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_connector_attach_passive_vrr_capable_property);
+
 /**
  * drm_connector_attach_scaling_mode_property - attach atomic scaling mode property
  * @connector: connector to attach scaling mode property on.
@@ -2968,6 +3020,27 @@ void drm_connector_set_vrr_capable_property(
 }
 EXPORT_SYMBOL(drm_connector_set_vrr_capable_property);
 
+/**
+ * drm_connector_set_passive_vrr_disabled_capable_property - sets the variable refresh
+ * rate on desktop capable property for a connector
+ * @connector: drm connector
+ * @capable: True if the connector is variable refresh rate on desktop capable
+ *
+ * Should be used by atomic drivers to update the indicated support for
+ * variable refresh rate on desktop over a connector.
+ */
+void drm_connector_set_passive_vrr_capable_property(
+		struct drm_connector *connector, bool capable)
+{
+	if (!connector->passive_vrr_capable_property)
+		return;
+
+	drm_object_property_set_value(&connector->base,
+				      connector->passive_vrr_capable_property,
+				      capable);
+}
+EXPORT_SYMBOL(drm_connector_set_passive_vrr_capable_property);
+
 /**
  * drm_connector_set_panel_orientation - sets the connector's panel_orientation
  * @connector: connector for which to set the panel-orientation property.
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index dab9d5521f41..30dd9737bfe0 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -2101,6 +2101,17 @@ struct drm_connector {
 	 */
 	struct drm_property *vrr_capable_property;
 
+	/**
+	 * @passive_vrr_capable_property: Optional property to help userspace
+	 * query hardware support for passive variable refresh rate on a
+	 * connector. Drivers can add the property to a connector by
+	 * calling drm_connector_attach_passive_vrr_capable_property().
+	 *
+	 * This should be updated only by calling
+	 * drm_connector_set_passive_vrr_capable_property().
+	 */
+	struct drm_property *passive_vrr_capable_property;
+
 	/**
 	 * @colorspace_property: Connector property to set the suitable
 	 * colorspace supported by the sink.
@@ -2495,6 +2506,8 @@ int drm_connector_attach_scaling_mode_property(struct drm_connector *connector,
 					       u32 scaling_mode_mask);
 int drm_connector_attach_vrr_capable_property(
 		struct drm_connector *connector);
+int drm_connector_attach_passive_vrr_capable_property(
+		struct drm_connector *connector);
 int drm_connector_attach_broadcast_rgb_property(struct drm_connector *connector);
 int drm_connector_attach_colorspace_property(struct drm_connector *connector);
 int drm_connector_attach_hdr_output_metadata_property(struct drm_connector *connector);
@@ -2517,6 +2530,8 @@ void drm_connector_set_link_status_property(struct drm_connector *connector,
 					    uint64_t link_status);
 void drm_connector_set_vrr_capable_property(
 		struct drm_connector *connector, bool capable);
+void drm_connector_set_passive_vrr_capable_property(
+		struct drm_connector *connector, bool capable);
 int drm_connector_set_panel_orientation(
 	struct drm_connector *connector,
 	enum drm_panel_orientation panel_orientation);
-- 
2.53.0