drm/bridge: tda998x: Add support for DRM_BRIDGE_ATTACH_NO_CONNECTOR

Add support for the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag to allow display
controller drivers to create their own connectors. This modernizes the
driver to work with the current DRM bridge framework.

The implementation includes:
- Refactoring detection and EDID reading into bridge-usable helpers
- Adding bridge operations: edid_read, detect, hpd_enable, hpd_disable
- Setting appropriate bridge ops (DRM_BRIDGE_OP_EDID, DRM_BRIDGE_OP_DETECT,
  DRM_BRIDGE_OP_HPD) and connector type (HDMIA)
- Skipping connector creation when DRM_BRIDGE_ATTACH_NO_CONNECTOR is set
- Handling conditional connector cleanup in bridge_detach

The driver maintains backward compatibility by continuing to create its
own connector when the flag is not set.

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20260123-feature_tilcdc-v5-24-5a44d2aa3f6f@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

drivers/gpu/drm/bridge/tda998x_drv.c

@@ -1193,16 +1193,22 @@ static int tda998x_audio_codec_init(struct tda998x_priv *priv,
 
 /* DRM connector functions */
 
-static enum drm_connector_status
+static enum drm_connector_status tda998x_conn_detect(struct tda998x_priv *priv)
-tda998x_connector_detect(struct drm_connector *connector, bool force)
 {
-	struct tda998x_priv *priv = conn_to_tda998x_priv(connector);
 	u8 val = cec_read(priv, REG_CEC_RXSHPDLEV);
 
 	return (val & CEC_RXSHPDLEV_HPD) ? connector_status_connected :
 			connector_status_disconnected;
 }
 
+static enum drm_connector_status
+tda998x_connector_detect(struct drm_connector *connector, bool force)
+{
+	struct tda998x_priv *priv = conn_to_tda998x_priv(connector);
+
+	return tda998x_conn_detect(priv);
+}
+
 static const struct drm_connector_funcs tda998x_connector_funcs = {
 	.reset = drm_atomic_helper_connector_reset,
 	.fill_modes = drm_helper_probe_single_connector_modes,
@@ -1276,11 +1282,10 @@ static int read_edid_block(void *data, u8 *buf, unsigned int blk, size_t length)
 	return ret;
 }
 
-static int tda998x_connector_get_modes(struct drm_connector *connector)
+static const struct drm_edid *tda998x_edid_read(struct tda998x_priv *priv,
+						struct drm_connector *connector)
 {
-	struct tda998x_priv *priv = conn_to_tda998x_priv(connector);
 	const struct drm_edid *drm_edid;
-	int n;
 
 	/*
 	 * If we get killed while waiting for the HPD timeout, return
@@ -1298,6 +1303,16 @@ static int tda998x_connector_get_modes(struct drm_connector *connector)
 	if (priv->rev == TDA19988)
 		reg_set(priv, REG_TX4, TX4_PD_RAM);
 
+	return drm_edid;
+}
+
+static int tda998x_connector_get_modes(struct drm_connector *connector)
+{
+	struct tda998x_priv *priv = conn_to_tda998x_priv(connector);
+	const struct drm_edid *drm_edid;
+	int n;
+
+	drm_edid = tda998x_edid_read(priv, connector);
 	drm_edid_connector_update(connector, drm_edid);
 	cec_notifier_set_phys_addr(priv->cec_notify,
 				   connector->display_info.source_physical_address);
@@ -1365,10 +1380,8 @@ static int tda998x_bridge_attach(struct drm_bridge *bridge,
 {
 	struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge);
 
-	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
-		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return 0;
-		return -EINVAL;
-	}
 
 	return tda998x_connector_init(priv, bridge->dev);
 }
@@ -1377,7 +1390,8 @@ static void tda998x_bridge_detach(struct drm_bridge *bridge)
 {
 	struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge);
 
-	drm_connector_cleanup(&priv->connector);
+	if (priv->connector.dev)
+		drm_connector_cleanup(&priv->connector);
 }
 
 static enum drm_mode_status tda998x_bridge_mode_valid(struct drm_bridge *bridge,
@@ -1677,6 +1691,59 @@ static void tda998x_bridge_mode_set(struct drm_bridge *bridge,
 	mutex_unlock(&priv->audio_mutex);
 }
 
+static const struct drm_edid *
+tda998x_bridge_edid_read(struct drm_bridge *bridge,
+			 struct drm_connector *connector)
+{
+	struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge);
+	const struct drm_edid *drm_edid;
+	const struct edid *edid;
+
+	drm_edid = tda998x_edid_read(priv, connector);
+	if (!drm_edid) {
+		dev_dbg(&priv->hdmi->dev, "failed to get edid\n");
+		return NULL;
+	}
+
+	/*
+	 * FIXME: This should use connector->display_info.has_audio from
+	 * a path that has read the EDID and called
+	 * drm_edid_connector_update().
+	 */
+	edid = drm_edid_raw(drm_edid);
+
+	dev_dbg(&priv->hdmi->dev, "got edid: width[%d] x height[%d]\n",
+		edid->width_cm, edid->height_cm);
+
+	priv->sink_has_audio = drm_detect_monitor_audio(edid);
+	cec_notifier_set_phys_addr_from_edid(priv->cec_notify, edid);
+
+	return drm_edid;
+}
+
+static enum drm_connector_status
+tda998x_bridge_detect(struct drm_bridge *bridge,
+		      struct drm_connector *connector)
+{
+	struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge);
+
+	return tda998x_conn_detect(priv);
+}
+
+static void tda998x_bridge_hpd_enable(struct drm_bridge *bridge)
+{
+	struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge);
+
+	cec_write(priv, REG_CEC_RXSHPDINTENA, CEC_RXSHPDLEV_HPD);
+}
+
+static void tda998x_bridge_hpd_disable(struct drm_bridge *bridge)
+{
+	struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge);
+
+	cec_write(priv, REG_CEC_RXSHPDINTENA, 0);
+}
+
 static const struct drm_bridge_funcs tda998x_bridge_funcs = {
 	.attach = tda998x_bridge_attach,
 	.detach = tda998x_bridge_detach,
@@ -1684,6 +1751,10 @@ static const struct drm_bridge_funcs tda998x_bridge_funcs = {
 	.disable = tda998x_bridge_disable,
 	.mode_set = tda998x_bridge_mode_set,
 	.enable = tda998x_bridge_enable,
+	.edid_read = tda998x_bridge_edid_read,
+	.detect = tda998x_bridge_detect,
+	.hpd_enable = tda998x_bridge_hpd_enable,
+	.hpd_disable = tda998x_bridge_hpd_disable,
 };
 
 /* I2C driver functions */
@@ -1872,6 +1943,7 @@ tda998x_probe(struct i2c_client *client)
 
 		/* enable HPD irq */
 		cec_write(priv, REG_CEC_RXSHPDINTENA, CEC_RXSHPDLEV_HPD);
+		priv->bridge.ops = DRM_BRIDGE_OP_HPD;
 	}
 
 	priv->cec_notify = cec_notifier_conn_register(dev, NULL, NULL);
@@ -1932,6 +2004,8 @@ tda998x_probe(struct i2c_client *client)
 	priv->bridge.of_node = dev->of_node;
 #endif
 
+	priv->bridge.ops |= DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_DETECT;
+	priv->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
 	drm_bridge_add(&priv->bridge);
 
 	return 0;