drm/connector: Introduce an HDMI connector initialization function

A lot of the various HDMI drivers duplicate some logic that depends on
the HDMI spec itself and not really a particular hardware
implementation.

Output BPC or format selection, infoframe generation are good examples
of such areas.

This creates a lot of boilerplate, with a lot of variations, which makes
it hard for userspace to rely on, and makes it difficult to get it right
for drivers.

In the next patches, we'll add a lot of infrastructure around the
drm_connector and drm_connector_state structures, which will allow to
abstract away the duplicated logic. This infrastructure comes with a few
requirements though, and thus we need a new initialization function.

Hopefully, this will make drivers simpler to handle, and their behaviour
more consistent.
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Sui Jingfeng <sui.jingfeng@linux.dev>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240527-kms-hdmi-connector-state-v15-1-c5af16c3aae2@kernel.orgSigned-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/drm_connector.c

@@ -452,6 +452,45 @@ int drmm_connector_init(struct drm_device *dev,
 }
 EXPORT_SYMBOL(drmm_connector_init);
 
+/**
+ * drmm_connector_hdmi_init - Init a preallocated HDMI connector
+ * @dev: DRM device
+ * @connector: A pointer to the HDMI connector to init
+ * @funcs: callbacks for this connector
+ * @connector_type: user visible type of the connector
+ * @ddc: optional pointer to the associated ddc adapter
+ *
+ * Initialises a preallocated HDMI connector. Connectors can be
+ * subclassed as part of driver connector objects.
+ *
+ * Cleanup is automatically handled with a call to
+ * drm_connector_cleanup() in a DRM-managed action.
+ *
+ * The connector structure should be allocated with drmm_kzalloc().
+ *
+ * Returns:
+ * Zero on success, error code on failure.
+ */
+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)
+{
+	int ret;
+
+	if (!(connector_type == DRM_MODE_CONNECTOR_HDMIA ||
+	      connector_type == DRM_MODE_CONNECTOR_HDMIB))
+		return -EINVAL;
+
+	ret = drmm_connector_init(dev, connector, funcs, connector_type, ddc);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL(drmm_connector_hdmi_init);
+
 /**
  * drm_connector_attach_edid_property - attach edid property.
  * @connector: the connector

include/drm/drm_connector.h

@@ -1908,6 +1908,11 @@ int drmm_connector_init(struct drm_device *dev,
 			const struct drm_connector_funcs *funcs,
 			int connector_type,
 			struct i2c_adapter *ddc);
+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);
 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);