drm/display/hdmi: implement hotplug functions

The HDMI Connectors need to perform a variety of tasks when the HDMI
connector state changes. Such tasks include setting or invalidating CEC
address, notifying HDMI codec driver, updating scrambler data, etc.

Implementing such tasks in a driver-specific callbacks is error prone.
Start implementing the generic helper function (currently handling only
the HDMI Codec framework) to be used by drivers utilizing HDMI Connector
framework.

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-v10-6-dc89577cd438@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

2 files changed, 58 insertions, 0 deletions

diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
index 2619fa2476eb..8d22b7627d41 100644
--- a/drivers/gpu/drm/display/Kconfig
+++ b/drivers/gpu/drm/display/Kconfig
@@ -89,6 +89,7 @@ config DRM_DISPLAY_HDMI_HELPER
 
 config DRM_DISPLAY_HDMI_STATE_HELPER
 	bool
+	select DRM_DISPLAY_HDMI_AUDIO_HELPER
 	select DRM_DISPLAY_HDMI_HELPER
 	help
 	  DRM KMS state helpers for HDMI.
diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
index d678c635a693..cfc2aaee1da0 100644
--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
@@ -5,6 +5,7 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_print.h>
 
+#include <drm/display/drm_hdmi_audio_helper.h>
 #include <drm/display/drm_hdmi_helper.h>
 #include <drm/display/drm_hdmi_state_helper.h>
 
@@ -777,3 +778,59 @@ drm_atomic_helper_connector_hdmi_clear_audio_infoframe(struct drm_connector *con
 	return ret;
 }
 EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_clear_audio_infoframe);
+
+static void
+drm_atomic_helper_connector_hdmi_update(struct drm_connector *connector,
+					enum drm_connector_status status)
+{
+	const struct drm_edid *drm_edid;
+
+	if (status == connector_status_disconnected) {
+		// TODO: also handle CEC and scramber, HDMI sink disconnected.
+		drm_connector_hdmi_audio_plugged_notify(connector, false);
+	}
+
+	if (connector->hdmi.funcs->read_edid)
+		drm_edid = connector->hdmi.funcs->read_edid(connector);
+	else
+		drm_edid = drm_edid_read(connector);
+
+	drm_edid_connector_update(connector, drm_edid);
+
+	drm_edid_free(drm_edid);
+
+	if (status == connector_status_connected) {
+		// TODO: also handle CEC and scramber, HDMI sink is now connected.
+		drm_connector_hdmi_audio_plugged_notify(connector, true);
+	}
+}
+
+/**
+ * drm_atomic_helper_connector_hdmi_hotplug - Handle the hotplug event for the HDMI connector
+ * @connector: A pointer to the HDMI connector
+ * @status: Connection status
+ *
+ * This function should be called as a part of the .detect() / .detect_ctx()
+ * callbacks, updating the HDMI-specific connector's data.
+ */
+void drm_atomic_helper_connector_hdmi_hotplug(struct drm_connector *connector,
+					      enum drm_connector_status status)
+{
+	drm_atomic_helper_connector_hdmi_update(connector, status);
+}
+EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_hotplug);
+
+/**
+ * drm_atomic_helper_connector_hdmi_force - HDMI Connector implementation of the force callback
+ * @connector: A pointer to the HDMI connector
+ *
+ * This function implements the .force() callback for the HDMI connectors. It
+ * can either be used directly as the callback or should be called from within
+ * the .force() callback implementation to maintain the HDMI-specific
+ * connector's data.
+ */
+void drm_atomic_helper_connector_hdmi_force(struct drm_connector *connector)
+{
+	drm_atomic_helper_connector_hdmi_update(connector, connector->status);
+}
+EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_force);