drm: Add vrr_enabled property to drm CRTC

This patch introduces the 'vrr_enabled' CRTC property to allow
dynamic control over variable refresh rate support for a CRTC.

This property should be treated like a content hint to the driver -
if the hardware or driver is not capable of driving variable refresh
timings then this is not considered an error.

Capability for variable refresh rate support should be determined
by querying the vrr_capable drm connector property.

It is worth noting that while the property is intended for atomic use
it isn't filtered from legacy userspace queries. This allows for Xorg
userspace drivers to implement support.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

5 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index d5b7f315098c..eec396a57b88 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -433,6 +433,8 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
 		ret = drm_atomic_set_mode_prop_for_crtc(state, mode);
 		drm_property_blob_put(mode);
 		return ret;
+	} else if (property == config->prop_vrr_enabled) {
+		state->vrr_enabled = val;
 	} else if (property == config->degamma_lut_property) {
 		ret = drm_atomic_replace_property_blob_from_id(dev,
 					&state->degamma_lut,
@@ -491,6 +493,8 @@ drm_atomic_crtc_get_property(struct drm_crtc *crtc,
 		*val = state->active;
 	else if (property == config->prop_mode_id)
 		*val = (state->mode_blob) ? state->mode_blob->base.id : 0;
+	else if (property == config->prop_vrr_enabled)
+		*val = state->vrr_enabled;
 	else if (property == config->degamma_lut_property)
 		*val = (state->degamma_lut) ? state->degamma_lut->base.id : 0;
 	else if (property == config->ctm_property)
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 268a182ae189..6f8ddfcfaba5 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -340,6 +340,8 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
 		drm_object_attach_property(&crtc->base, config->prop_mode_id, 0);
 		drm_object_attach_property(&crtc->base,
 					   config->prop_out_fence_ptr, 0);
+		drm_object_attach_property(&crtc->base,
+					   config->prop_vrr_enabled, 0);
 	}
 
 	return 0;
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index ee80788f2c40..5670c67f28d4 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -310,6 +310,12 @@ 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,
+			"VRR_ENABLED");
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.prop_vrr_enabled = prop;
+
 	prop = drm_property_create(dev,
 			DRM_MODE_PROP_BLOB,
 			"DEGAMMA_LUT", 0);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index b21437bc95bf..39c3900aab3c 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -291,6 +291,15 @@ struct drm_crtc_state {
 	u32 pageflip_flags;
 
 	/**
+	 * @vrr_enabled:
+	 *
+	 * Indicates if variable refresh rate should be enabled for the CRTC.
+	 * Support for the requested vrr state will depend on driver and
+	 * hardware capabiltiy - lacking support is not treated as failure.
+	 */
+	bool vrr_enabled;
+
+	/**
 	 * @event:
 	 *
 	 * Optional pointer to a DRM event to signal upon completion of the
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index 5dbeabdbaf91..9db59a1caf5b 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -645,6 +645,11 @@ struct drm_mode_config {
 	 * connectors must be of and active must be set to disabled, too.
 	 */
 	struct drm_property *prop_mode_id;
+	/**
+	 * @prop_vrr_enabled: Default atomic CRTC property to indicate
+	 * whether variable refresh rate should be enabled on the CRTC.
+	 */
+	struct drm_property *prop_vrr_enabled;
 
 	/**
 	 * @dvi_i_subconnector_property: Optional DVI-I property to