[PATCH v2 1/3] drm: Add variable refresh rate properties to connector

[Nicholas Kazlauskas]

Modern display hardware is capable of supporting variable refresh rates
and adaptive sync technologies. The properties for querying and
controlling these features should be exposed on the DRM connector.

This patch introduces two new properties for variable refresh rate
support:

- variable_refresh_capable
- variable_refresh_enabled

These are optional properties that can be added to a DRM connector
dynamically by using drm_connector_attach_variable_refresh_properties.

DRM drivers should set variable_refresh_capable as applicable for
their hardware. The property variable_refresh_enabled is a userspace
controlled option.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
---
 drivers/gpu/drm/drm_atomic_uapi.c |  6 ++++++
 drivers/gpu/drm/drm_connector.c   | 35 +++++++++++++++++++++++++++++++
 include/drm/drm_connector.h       | 27 ++++++++++++++++++++++++
 3 files changed, 68 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index d5b7f315098c..0bb27a24a55c 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -723,6 +723,8 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector,
 		state->content_type = val;
 	} else if (property == connector->scaling_mode_property) {
 		state->scaling_mode = val;
+	} else if (property == connector->variable_refresh_enabled_property) {
+		state->variable_refresh_enabled = val;
 	} else if (property == connector->content_protection_property) {
 		if (val == DRM_MODE_CONTENT_PROTECTION_ENABLED) {
 			DRM_DEBUG_KMS("only drivers can set CP Enabled\n");
@@ -797,6 +799,10 @@ drm_atomic_connector_get_property(struct drm_connector *connector,
 		*val = state->content_type;
 	} else if (property == connector->scaling_mode_property) {
 		*val = state->scaling_mode;
+	} else if (property == connector->variable_refresh_capable_property) {
+		*val = state->variable_refresh_capable;
+	} else if (property == connector->variable_refresh_enabled_property) {
+		*val = state->variable_refresh_enabled;
 	} else if (property == connector->content_protection_property) {
 		*val = state->content_protection;
 	} else if (property == config->writeback_fb_id_property) {
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 1e40e5decbe9..fc1732639bd3 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1254,6 +1254,41 @@ int drm_mode_create_scaling_mode_property(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_mode_create_scaling_mode_property);
 
+/**
+ * drm_connector_attach_variable_refresh_properties - creates and attaches
+ * properties for connectors that support adaptive refresh
+ * @connector: connector to create adaptive refresh properties on
+ */
+int drm_connector_attach_variable_refresh_properties(
+	struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_property *prop;
+
+	if (!connector->variable_refresh_capable_property) {
+		prop = drm_property_create_bool(dev, DRM_MODE_PROP_IMMUTABLE,
+			"variable_refresh_capable");
+		if (!prop)
+			return -ENOMEM;
+
+		connector->variable_refresh_capable_property = prop;
+		drm_object_attach_property(&connector->base, prop, 0);
+	}
+
+	if (!connector->variable_refresh_enabled_property) {
+		prop = drm_property_create_bool(dev, 0,
+			"variable_refresh_enabled");
+		if (!prop)
+			return -ENOMEM;
+
+		connector->variable_refresh_enabled_property = prop;
+		drm_object_attach_property(&connector->base, prop, 0);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_connector_attach_variable_refresh_properties);
+
 /**
  * drm_connector_attach_scaling_mode_property - attach atomic scaling mode property
  * @connector: connector to attach scaling mode property on.
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 91a877fa00cb..e2c26842bd50 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -449,6 +449,18 @@ struct drm_connector_state {
 	 */
 	unsigned int content_protection;
 
+	/**
+	 * @variable_refresh_enabled: Connector property used to check
+	 * if variable refresh is supported on the device.
+	 */
+	bool variable_refresh_capable;
+
+	/**
+	 * @variable_refresh_enabled: Connector property used to check
+	 * if variable refresh is enabled.
+	 */
+	bool variable_refresh_enabled;
+
 	/**
 	 * @writeback_job: Writeback job for writeback connectors
 	 *
@@ -910,6 +922,19 @@ struct drm_connector {
 	 */
 	struct drm_property *scaling_mode_property;
 
+	/**
+	 * @variable_refresh_capable_property: Optional property for
+	 * querying hardware support for variable refresh.
+	 */
+	struct drm_property *variable_refresh_capable_property;
+
+	/**
+	 * @variable_refresh_enabled_property: Optional property for
+	 * enabling or disabling support for variable refresh
+	 * on the connector.
+	 */
+	struct drm_property *variable_refresh_enabled_property;
+
 	/**
 	 * @content_protection_property: DRM ENUM property for content
 	 * protection. See drm_connector_attach_content_protection_property().
@@ -1183,6 +1208,8 @@ int drm_mode_create_scaling_mode_property(struct drm_device *dev);
 int drm_connector_attach_content_type_property(struct drm_connector *dev);
 int drm_connector_attach_scaling_mode_property(struct drm_connector *connector,
 					       u32 scaling_mode_mask);
+int drm_connector_attach_variable_refresh_properties(
+	struct drm_connector *connector);
 int drm_connector_attach_content_protection_property(
 		struct drm_connector *connector);
 int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
-- 
2.19.0