drm/connector: hdmi: Add output BPC to the connector state

We'll add automatic selection of the output BPC in a following patch,
but let's add it to the HDMI connector state already.
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240527-kms-hdmi-connector-state-v15-4-c5af16c3aae2@kernel.orgSigned-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/display/drm_hdmi_state_helper.c

@@ -18,6 +18,10 @@
 void __drm_atomic_helper_connector_hdmi_reset(struct drm_connector *connector,
 					      struct drm_connector_state *new_conn_state)
 {
+	unsigned int max_bpc = connector->max_bpc;
+
+	new_conn_state->max_bpc = max_bpc;
+	new_conn_state->max_requested_bpc = max_bpc;
 }
 EXPORT_SYMBOL(__drm_atomic_helper_connector_hdmi_reset);
 
@@ -36,6 +40,22 @@ EXPORT_SYMBOL(__drm_atomic_helper_connector_hdmi_reset);
 int drm_atomic_helper_connector_hdmi_check(struct drm_connector *connector,
 					   struct drm_atomic_state *state)
 {
+	struct drm_connector_state *old_conn_state =
+		drm_atomic_get_old_connector_state(state, connector);
+	struct drm_connector_state *new_conn_state =
+		drm_atomic_get_new_connector_state(state, connector);
+
+	if (old_conn_state->hdmi.output_bpc != new_conn_state->hdmi.output_bpc) {
+		struct drm_crtc *crtc = new_conn_state->crtc;
+		struct drm_crtc_state *crtc_state;
+
+		crtc_state = drm_atomic_get_crtc_state(state, crtc);
+		if (IS_ERR(crtc_state))
+			return PTR_ERR(crtc_state);
+
+		crtc_state->mode_changed = true;
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_check);

drivers/gpu/drm/drm_atomic.c

@@ -1143,6 +1143,11 @@ static void drm_atomic_connector_print_state(struct drm_printer *p,
 	drm_printf(p, "\tmax_requested_bpc=%d\n", state->max_requested_bpc);
 	drm_printf(p, "\tcolorspace=%s\n", drm_get_colorspace_name(state->colorspace));
 
+	if (connector->connector_type == DRM_MODE_CONNECTOR_HDMIA ||
+	    connector->connector_type == DRM_MODE_CONNECTOR_HDMIB) {
+		drm_printf(p, "\toutput_bpc=%u\n", state->hdmi.output_bpc);
+	}
+
 	if (connector->connector_type == DRM_MODE_CONNECTOR_WRITEBACK)
 		if (state->writeback_job && state->writeback_job->fb)
 			drm_printf(p, "\tfb=%d\n", state->writeback_job->fb->base.id);

drivers/gpu/drm/drm_connector.c

@@ -459,6 +459,7 @@ EXPORT_SYMBOL(drmm_connector_init);
  * @funcs: callbacks for this connector
  * @connector_type: user visible type of the connector
  * @ddc: optional pointer to the associated ddc adapter
+ * @max_bpc: Maximum bits per char the HDMI connector supports
  *
  * Initialises a preallocated HDMI connector. Connectors can be
  * subclassed as part of driver connector objects.
@@ -475,7 +476,8 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
 			     struct drm_connector *connector,
 			     const struct drm_connector_funcs *funcs,
 			     int connector_type,
-			     struct i2c_adapter *ddc)
+			     struct i2c_adapter *ddc,
+			     unsigned int max_bpc)
 {
 	int ret;
 
@@ -483,10 +485,26 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
 	      connector_type == DRM_MODE_CONNECTOR_HDMIB))
 		return -EINVAL;
 
+	if (!(max_bpc == 8 || max_bpc == 10 || max_bpc == 12))
+		return -EINVAL;
+
 	ret = drmm_connector_init(dev, connector, funcs, connector_type, ddc);
 	if (ret)
 		return ret;
 
+	/*
+	 * drm_connector_attach_max_bpc_property() requires the
+	 * connector to have a state.
+	 */
+	if (connector->funcs->reset)
+		connector->funcs->reset(connector);
+
+	drm_connector_attach_max_bpc_property(connector, 8, max_bpc);
+	connector->max_bpc = max_bpc;
+
+	if (max_bpc > 8)
+		drm_connector_attach_hdr_output_metadata_property(connector);
+
 	return 0;
 }
 EXPORT_SYMBOL(drmm_connector_hdmi_init);

drivers/gpu/drm/tests/drm_connector_test.c

@@ -184,7 +184,8 @@ static void drm_test_connector_hdmi_init_valid(struct kunit *test)
 	ret = drmm_connector_hdmi_init(&priv->drm, &priv->connector,
 				       &dummy_funcs,
 				       DRM_MODE_CONNECTOR_HDMIA,
-				       &priv->ddc);
+				       &priv->ddc,
+				       8);
 	KUNIT_EXPECT_EQ(test, ret, 0);
 }
 
@@ -200,7 +201,8 @@ static void drm_test_connector_hdmi_init_null_ddc(struct kunit *test)
 	ret = drmm_connector_hdmi_init(&priv->drm, &priv->connector,
 				       &dummy_funcs,
 				       DRM_MODE_CONNECTOR_HDMIA,
-				       NULL);
+				       NULL,
+				       8);
 	KUNIT_EXPECT_EQ(test, ret, 0);
 }
 
@@ -217,7 +219,8 @@ static void drm_test_connector_hdmi_init_type_valid(struct kunit *test)
 	ret = drmm_connector_hdmi_init(&priv->drm, &priv->connector,
 				       &dummy_funcs,
 				       connector_type,
-				       &priv->ddc);
+				       &priv->ddc,
+				       8);
 	KUNIT_EXPECT_EQ(test, ret, 0);
 }
 
@@ -248,7 +251,8 @@ static void drm_test_connector_hdmi_init_type_invalid(struct kunit *test)
 	ret = drmm_connector_hdmi_init(&priv->drm, &priv->connector,
 				       &dummy_funcs,
 				       connector_type,
-				       &priv->ddc);
+				       &priv->ddc,
+				       8);
 	KUNIT_EXPECT_LT(test, ret, 0);
 }
 

include/drm/drm_connector.h

@@ -1037,6 +1037,10 @@ struct drm_connector_state {
 	 * @drm_atomic_helper_connector_hdmi_check().
 	 */
 	struct {
+		/**
+		 * @output_bpc: Bits per color channel to output.
+		 */
+		unsigned int output_bpc;
 	} hdmi;
 };
 
@@ -1686,6 +1690,11 @@ struct drm_connector {
 	 */
 	struct drm_property_blob *path_blob_ptr;
 
+	/**
+	 * @max_bpc: Maximum bits per color channel the connector supports.
+	 */
+	unsigned int max_bpc;
+
 	/**
 	 * @max_bpc_property: Default connector property for the max bpc to be
 	 * driven out of the connector.
@@ -1919,7 +1928,8 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
 			     struct drm_connector *connector,
 			     const struct drm_connector_funcs *funcs,
 			     int connector_type,
-			     struct i2c_adapter *ddc);
+			     struct i2c_adapter *ddc,
+			     unsigned int max_bpc);
 void drm_connector_attach_edid_property(struct drm_connector *connector);
 int drm_connector_register(struct drm_connector *connector);
 void drm_connector_unregister(struct drm_connector *connector);