drm: Add passive_vrr_disabled property to crtc

Many TVs and other HDMI sinks suffer from blanking and possibly other
glitches when VRR is toggled. With VRR present on such sinks and
vrr_on_desktop enabled, they behave like the signal is always variable,
even in fixed refresh rate situations. DisplayPort and eDP enforce
seamless VRR transitions but HDMI unfortunately doesn't.

Keep VRR toggled if it's supported and not explicitly disabled. It can
be used for any VRR sinks, but this is mainly targeted for HDMI.

Functionally, for an end user, this is the same as normal, fixed refresh
rate mode. The only difference is that sink is kept in VRR state which
enables seamless transitions into/out of variable refresh rate.

Basically, the driver shouldn't change it's behavior around VRR_ENABLED
set to false, jut keep sending info packets/frames with VRR/FreeSync/
G-Sync/HDMI VRR active.

Enabled by default for sinks that claim it's support

Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com>

Author: Lawstorant

drivers/gpu/drm/drm_atomic_uapi.c

@@ -412,6 +412,8 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
 		return ret;
 	} else if (property == config->prop_vrr_enabled) {
 		state->vrr_enabled = val;
+	} else if (property == config->prop_passive_vrr_disabled) {
+		state->passive_vrr_disabled = val;
 	} else if (property == config->degamma_lut_property) {
 		const size_t elem_size = sizeof(struct drm_color_lut);
 		u64 lut_size;
@@ -495,6 +497,8 @@ drm_atomic_crtc_get_property(struct drm_crtc *crtc,
 		*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->prop_passive_vrr_disabled)
+		*val = state->passive_vrr_disabled;
 	else if (property == config->degamma_lut_property)
 		*val = (state->degamma_lut) ? state->degamma_lut->base.id : 0;
 	else if (property == config->ctm_property)

drivers/gpu/drm/drm_crtc.c

@@ -322,6 +322,8 @@ static int __drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *
 					   config->prop_out_fence_ptr, 0);
 		drm_object_attach_property(&crtc->base,
 					   config->prop_vrr_enabled, 0);
+		drm_object_attach_property(&crtc->base,
+					   config->prop_passive_vrr_disabled, 0);
 	}
 
 	return 0;

drivers/gpu/drm/drm_mode_config.c

@@ -345,6 +345,12 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
 		return -ENOMEM;
 	dev->mode_config.prop_vrr_enabled = prop;
 
+	prop = drm_property_create_bool(dev, 0,
+			"PASSIVE_VRR_DISABLED");
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.prop_passive_vrr_disabled = prop;
+
 	prop = drm_property_create(dev,
 			DRM_MODE_PROP_BLOB,
 			"DEGAMMA_LUT", 0);

include/drm/drm_crtc.h

@@ -299,6 +299,15 @@ struct drm_crtc_state {
 	 */
 	bool vrr_enabled;
 
+	/**
+	 * @passive_vrr_disabled:
+	 *
+	 * Indicates if variable refresh rate on desktop should be enabled for
+	 * the CRTC. Support for the requested state will depend on driver and
+	 * hardware capabiltiy - lacking support is not treated as failure.
+	 */
+	bool passive_vrr_disabled;
+
 	/**
 	 * @self_refresh_active:
 	 *

include/drm/drm_mode_config.h

@@ -697,6 +697,12 @@ struct drm_mode_config {
 	 * whether variable refresh rate should be enabled on the CRTC.
 	 */
 	struct drm_property *prop_vrr_enabled;
+	/**
+	 * @prop_passive_vrr_disabled: Default atomic CRTC property to indicate
+	 * whether passive variable refresh rate should be disabled
+	 * on the CRTC.
+	 */
+	struct drm_property *prop_passive_vrr_disabled;
 
 	/**
 	 * @dvi_i_subconnector_property: Optional DVI-I property to