[RFC v2 1/2] drm/vrr: Attach vrr_enabled property to the drm crtc

[Bhanuprakash Modem]

Modern display hardware is capable of supporting variable refresh rates.
This patch introduces helpers to attach and set "vrr_enabled" property
on the crtc to allow userspace to query VRR enabled status on that crtc.

Atomic drivers should attach this property to crtcs those are capable of
driving variable refresh rates using
drm_mode_crtc_attach_vrr_enabled_property().

The value should be updated based on driver and hardware capability
by using drm_mode_crtc_set_vrr_enabled_property().

V2: Use property flag as atomic

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
Cc: Manasi Navare <manasi.d.navare at intel.com>
Cc: Harry Wentland <harry.wentland at amd.com>
Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
---
 drivers/gpu/drm/drm_crtc.c        | 44 +++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_mode_config.c |  2 +-
 include/drm/drm_crtc.h            |  4 +++
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 26a77a735905..95b4a0c7ecb3 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -883,3 +883,47 @@ int drm_crtc_create_scaling_filter_property(struct drm_crtc *crtc,
 	return 0;
 }
 EXPORT_SYMBOL(drm_crtc_create_scaling_filter_property);
+
+/**
+ * drm_mode_crtc_attach_vrr_enabled_property - attaches the vrr_enabled property
+ * @crtc: drm CRTC to attach the vrr_enabled property on.
+ *
+ * This is used by atomic drivers to add support for querying
+ * VRR enabled status for a crtc.
+ */
+void drm_mode_crtc_attach_vrr_enabled_property(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_mode_config *config = &dev->mode_config;
+
+	if (!config->prop_vrr_enabled)
+		return;
+
+	drm_object_attach_property(&crtc->base,
+				   config->prop_vrr_enabled,
+				   0);
+}
+EXPORT_SYMBOL(drm_mode_crtc_attach_vrr_enabled_property);
+
+/**
+ * drm_mode_crtc_set_vrr_enabled_property - sets the vrr enabled property for
+ * a crtc.
+ * @crtc: drm CRTC
+ * @vrr_enabled: True to enable the VRR on CRTC
+ *
+ * Should be used by atomic drivers to update the VRR enabled status on a CRTC
+ */
+void drm_mode_crtc_set_vrr_enabled_property(struct drm_crtc *crtc,
+					    bool vrr_enabled)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_mode_config *config = &dev->mode_config;
+
+	if (!config->prop_vrr_enabled)
+		return;
+
+	drm_object_property_set_value(&crtc->base,
+				      config->prop_vrr_enabled,
+				      vrr_enabled);
+}
+EXPORT_SYMBOL(drm_mode_crtc_set_vrr_enabled_property);
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 37b4b9f0e468..b7cde73d5586 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -323,7 +323,7 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
 		return -ENOMEM;
 	dev->mode_config.prop_mode_id = prop;
 
-	prop = drm_property_create_bool(dev, 0,
+	prop = drm_property_create_bool(dev, DRM_MODE_PROP_ATOMIC,
 			"VRR_ENABLED");
 	if (!prop)
 		return -ENOMEM;
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index a70baea0636c..bde657cb0f9e 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1333,4 +1333,8 @@ static inline struct drm_crtc *drm_crtc_find(struct drm_device *dev,
 int drm_crtc_create_scaling_filter_property(struct drm_crtc *crtc,
 					    unsigned int supported_filters);
 
+void drm_mode_crtc_attach_vrr_enabled_property(struct drm_crtc *crtc);
+void drm_mode_crtc_set_vrr_enabled_property(struct drm_crtc *crtc,
+					    bool vrr_enabled);
+
 #endif /* __DRM_CRTC_H__ */
-- 
2.35.1