drm/connector: Add helper to compare HDR metadata

All the drivers that support the HDR metadata property have a similar
function to compare the metadata from one connector state to the next,
and force a mode change if they differ.

All these functions run pretty much the same code, so let's turn it into
an helper that can be shared across those drivers.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210430094451.2145002-2-maxime@cerno.tech

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -6275,25 +6275,6 @@ static int fill_hdr_info_packet(const struct drm_connector_state *state,
 	return 0;
 }
 
-static bool
-is_hdr_metadata_different(const struct drm_connector_state *old_state,
-			  const struct drm_connector_state *new_state)
-{
-	struct drm_property_blob *old_blob = old_state->hdr_output_metadata;
-	struct drm_property_blob *new_blob = new_state->hdr_output_metadata;
-
-	if (old_blob != new_blob) {
-		if (old_blob && new_blob &&
-		    old_blob->length == new_blob->length)
-			return memcmp(old_blob->data, new_blob->data,
-				      old_blob->length);
-
-		return true;
-	}
-
-	return false;
-}
-
 static int
 amdgpu_dm_connector_atomic_check(struct drm_connector *conn,
 				 struct drm_atomic_state *state)
@@ -6311,7 +6292,7 @@ amdgpu_dm_connector_atomic_check(struct drm_connector *conn,
 	if (!crtc)
 		return 0;
 
-	if (is_hdr_metadata_different(old_con_state, new_con_state)) {
+	if (!drm_connector_atomic_hdr_metadata_equal(old_con_state, new_con_state)) {
 		struct dc_info_packet hdr_infopacket;
 
 		ret = fill_hdr_info_packet(new_con_state, &hdr_infopacket);
@@ -8803,7 +8784,7 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 			      dm_old_crtc_state->abm_level;
 
 		hdr_changed =
-			is_hdr_metadata_different(old_con_state, new_con_state);
+			!drm_connector_atomic_hdr_metadata_equal(old_con_state, new_con_state);
 
 		if (!scaling_changed && !abm_changed && !hdr_changed)
 			continue;

drivers/gpu/drm/bridge/synopsys/dw-hdmi.c

@@ -2395,21 +2395,6 @@ static int dw_hdmi_connector_get_modes(struct drm_connector *connector)
 	return ret;
 }
 
-static bool hdr_metadata_equal(const struct drm_connector_state *old_state,
-			       const struct drm_connector_state *new_state)
-{
-	struct drm_property_blob *old_blob = old_state->hdr_output_metadata;
-	struct drm_property_blob *new_blob = new_state->hdr_output_metadata;
-
-	if (!old_blob || !new_blob)
-		return old_blob == new_blob;
-
-	if (old_blob->length != new_blob->length)
-		return false;
-
-	return !memcmp(old_blob->data, new_blob->data, old_blob->length);
-}
-
 static int dw_hdmi_connector_atomic_check(struct drm_connector *connector,
 					  struct drm_atomic_state *state)
 {
@@ -2423,7 +2408,7 @@ static int dw_hdmi_connector_atomic_check(struct drm_connector *connector,
 	if (!crtc)
 		return 0;
 
-	if (!hdr_metadata_equal(old_state, new_state)) {
+	if (!drm_connector_atomic_hdr_metadata_equal(old_state, new_state)) {
 		crtc_state = drm_atomic_get_crtc_state(state, crtc);
 		if (IS_ERR(crtc_state))
 			return PTR_ERR(crtc_state);

drivers/gpu/drm/drm_connector.c

@@ -2173,6 +2173,34 @@ int drm_connector_attach_hdr_output_metadata_property(struct drm_connector *conn
 }
 EXPORT_SYMBOL(drm_connector_attach_hdr_output_metadata_property);
 
+/**
+ * drm_connector_atomic_hdr_metadata_equal - checks if the hdr metadata changed
+ * @old_state: old connector state to compare
+ * @new_state: new connector state to compare
+ *
+ * This is used by HDR-enabled drivers to test whether the HDR metadata
+ * have changed between two different connector state (and thus probably
+ * requires a full blown mode change).
+ *
+ * Returns:
+ * True if the metadata are equal, False otherwise
+ */
+bool drm_connector_atomic_hdr_metadata_equal(struct drm_connector_state *old_state,
+					     struct drm_connector_state *new_state)
+{
+	struct drm_property_blob *old_blob = old_state->hdr_output_metadata;
+	struct drm_property_blob *new_blob = new_state->hdr_output_metadata;
+
+	if (!old_blob || !new_blob)
+		return old_blob == new_blob;
+
+	if (old_blob->length != new_blob->length)
+		return false;
+
+	return !memcmp(old_blob->data, new_blob->data, old_blob->length);
+}
+EXPORT_SYMBOL(drm_connector_atomic_hdr_metadata_equal);
+
 /**
  * drm_connector_set_vrr_capable_property - sets the variable refresh rate
  * capable property for a connector

drivers/gpu/drm/i915/display/intel_atomic.c

@@ -109,16 +109,6 @@ int intel_digital_connector_atomic_set_property(struct drm_connector *connector,
 	return -EINVAL;
 }
 
-static bool blob_equal(const struct drm_property_blob *a,
-		       const struct drm_property_blob *b)
-{
-	if (a && b)
-		return a->length == b->length &&
-			!memcmp(a->data, b->data, a->length);
-
-	return !a == !b;
-}
-
 int intel_digital_connector_atomic_check(struct drm_connector *conn,
 					 struct drm_atomic_state *state)
 {
@@ -149,8 +139,7 @@ int intel_digital_connector_atomic_check(struct drm_connector *conn,
 	    new_conn_state->base.picture_aspect_ratio != old_conn_state->base.picture_aspect_ratio ||
 	    new_conn_state->base.content_type != old_conn_state->base.content_type ||
 	    new_conn_state->base.scaling_mode != old_conn_state->base.scaling_mode ||
-	    !blob_equal(new_conn_state->base.hdr_output_metadata,
-			old_conn_state->base.hdr_output_metadata))
+	    !drm_connector_atomic_hdr_metadata_equal(old_state, new_state))
 		crtc_state->mode_changed = true;
 
 	return 0;

include/drm/drm_connector.h

@@ -1672,6 +1672,8 @@ int drm_connector_attach_scaling_mode_property(struct drm_connector *connector,
 int drm_connector_attach_vrr_capable_property(
 		struct drm_connector *connector);
 int drm_connector_attach_hdr_output_metadata_property(struct drm_connector *connector);
+bool drm_connector_atomic_hdr_metadata_equal(struct drm_connector_state *old_state,
+					     struct drm_connector_state *new_state);
 int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
 int drm_mode_create_hdmi_colorspace_property(struct drm_connector *connector);
 int drm_mode_create_dp_colorspace_property(struct drm_connector *connector);