drm/bridge_connector: hook drm_atomic_helper_connector_hdmi_hotplug()

Extend drm_bridge_connector code to read the EDID and use it to update
connector status if the bridge chain implements HDMI bridge. Performing
it from the generic location minimizes individual bridge's code and
enforces standard behaviour from all corresponding drivers.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241224-drm-bridge-hdmi-connector-v10-7-dc89577cd438@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Author: lumag

drivers/gpu/drm/display/drm_bridge_connector.c

@@ -17,6 +17,7 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/display/drm_hdmi_audio_helper.h>
 #include <drm/display/drm_hdmi_helper.h>
@@ -181,11 +182,15 @@ drm_bridge_connector_detect(struct drm_connector *connector, bool force)
 	struct drm_bridge_connector *bridge_connector =
 		to_drm_bridge_connector(connector);
 	struct drm_bridge *detect = bridge_connector->bridge_detect;
+	struct drm_bridge *hdmi = bridge_connector->bridge_hdmi;
 	enum drm_connector_status status;
 
 	if (detect) {
 		status = detect->funcs->detect(detect);
 
+		if (hdmi)
+			drm_atomic_helper_connector_hdmi_hotplug(connector, status);
+
 		drm_bridge_connector_hpd_notify(connector, status);
 	} else {
 		switch (connector->connector_type) {
@@ -204,6 +209,16 @@ drm_bridge_connector_detect(struct drm_connector *connector, bool force)
 	return status;
 }
 
+static void drm_bridge_connector_force(struct drm_connector *connector)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *hdmi = bridge_connector->bridge_hdmi;
+
+	if (hdmi)
+		drm_atomic_helper_connector_hdmi_force(connector);
+}
+
 static void drm_bridge_connector_debugfs_init(struct drm_connector *connector,
 					      struct dentry *root)
 {
@@ -232,6 +247,7 @@ static void drm_bridge_connector_reset(struct drm_connector *connector)
 static const struct drm_connector_funcs drm_bridge_connector_funcs = {
 	.reset = drm_bridge_connector_reset,
 	.detect = drm_bridge_connector_detect,
+	.force = drm_bridge_connector_force,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
@@ -277,6 +293,14 @@ static int drm_bridge_connector_get_modes(struct drm_connector *connector)
 		to_drm_bridge_connector(connector);
 	struct drm_bridge *bridge;
 
+	/*
+	 * If there is a HDMI bridge, EDID has been updated as a part of
+	 * the .detect(). Just update the modes here.
+	 */
+	bridge = bridge_connector->bridge_hdmi;
+	if (bridge)
+		return drm_edid_connector_add_modes(connector);
+
 	/*
 	 * If display exposes EDID, then we parse that in the normal way to
 	 * build table of supported modes.
@@ -382,10 +406,25 @@ static int drm_bridge_connector_write_infoframe(struct drm_connector *connector,
 	return bridge->funcs->hdmi_write_infoframe(bridge, type, buffer, len);
 }
 
+static const struct drm_edid *
+drm_bridge_connector_read_edid(struct drm_connector *connector)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *bridge;
+
+	bridge = bridge_connector->bridge_edid;
+	if (!bridge)
+		return NULL;
+
+	return drm_bridge_edid_read(bridge, connector);
+}
+
 static const struct drm_connector_hdmi_funcs drm_bridge_connector_hdmi_funcs = {
 	.tmds_char_rate_valid = drm_bridge_connector_tmds_char_rate_valid,
 	.clear_infoframe = drm_bridge_connector_clear_infoframe,
 	.write_infoframe = drm_bridge_connector_write_infoframe,
+	.read_edid = drm_bridge_connector_read_edid,
 };
 
 static int drm_bridge_connector_audio_startup(struct drm_connector *connector)