2 files changed, 66 insertions, 14 deletions

diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
index 9e0b845be7cb..99fd15d1b366 100644
--- a/drivers/gpu/drm/drm_writeback.c
+++ b/drivers/gpu/drm/drm_writeback.c
@@ -178,6 +178,62 @@ int drm_writeback_connector_init(struct drm_device *dev,
 				 const u32 *formats, int n_formats,
 				 u32 possible_crtcs)
 {
+	int ret = 0;
+
+	drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs);
+
+	wb_connector->encoder.possible_crtcs = possible_crtcs;
+
+	ret = drm_encoder_init(dev, &wb_connector->encoder,
+			       &drm_writeback_encoder_funcs,
+			       DRM_MODE_ENCODER_VIRTUAL, NULL);
+	if (ret)
+		return ret;
+
+	ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, &wb_connector->encoder,
+			con_funcs, formats, n_formats);
+
+	if (ret)
+		drm_encoder_cleanup(&wb_connector->encoder);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_writeback_connector_init);
+
+/**
+ * drm_writeback_connector_init_with_encoder - Initialize a writeback connector with
+ * a custom encoder
+ *
+ * @dev: DRM device
+ * @wb_connector: Writeback connector to initialize
+ * @enc: handle to the already initialized drm encoder
+ * @con_funcs: Connector funcs vtable
+ * @formats: Array of supported pixel formats for the writeback engine
+ * @n_formats: Length of the formats array
+ *
+ * This function creates the writeback-connector-specific properties if they
+ * have not been already created, initializes the connector as
+ * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
+ * values.
+ *
+ * This function assumes that the drm_writeback_connector's encoder has already been
+ * created and initialized before invoking this function.
+ *
+ * In addition, this function also assumes that callers of this API will manage
+ * assigning the encoder helper functions, possible_crtcs and any other encoder
+ * specific operation.
+ *
+ * Drivers should always use this function instead of drm_connector_init() to
+ * set up writeback connectors if they want to manage themselves the lifetime of the
+ * associated encoder.
+ *
+ * Returns: 0 on success, or a negative error code
+ */
+int drm_writeback_connector_init_with_encoder(struct drm_device *dev,
+		struct drm_writeback_connector *wb_connector, struct drm_encoder *enc,
+		const struct drm_connector_funcs *con_funcs, const u32 *formats,
+		int n_formats)
+{
 	struct drm_property_blob *blob;
 	struct drm_connector *connector = &wb_connector->base;
 	struct drm_mode_config *config = &dev->mode_config;
@@ -191,15 +247,6 @@ int drm_writeback_connector_init(struct drm_device *dev,
 	if (IS_ERR(blob))
 		return PTR_ERR(blob);
 
-	drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs);
-
-	wb_connector->encoder.possible_crtcs = possible_crtcs;
-
-	ret = drm_encoder_init(dev, &wb_connector->encoder,
-			       &drm_writeback_encoder_funcs,
-			       DRM_MODE_ENCODER_VIRTUAL, NULL);
-	if (ret)
-		goto fail;
 
 	connector->interlace_allowed = 0;
 
@@ -208,8 +255,7 @@ int drm_writeback_connector_init(struct drm_device *dev,
 	if (ret)
 		goto connector_fail;
 
-	ret = drm_connector_attach_encoder(connector,
-						&wb_connector->encoder);
+	ret = drm_connector_attach_encoder(connector, enc);
 	if (ret)
 		goto attach_fail;
 
@@ -238,12 +284,10 @@ int drm_writeback_connector_init(struct drm_device *dev,
 attach_fail:
 	drm_connector_cleanup(connector);
 connector_fail:
-	drm_encoder_cleanup(&wb_connector->encoder);
-fail:
 	drm_property_blob_put(blob);
 	return ret;
 }
-EXPORT_SYMBOL(drm_writeback_connector_init);
+EXPORT_SYMBOL(drm_writeback_connector_init_with_encoder);
 
 int drm_writeback_set_fb(struct drm_connector_state *conn_state,
 			 struct drm_framebuffer *fb)
diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h
index 5d9263fdbd84..17e576c80169 100644
--- a/include/drm/drm_writeback.h
+++ b/include/drm/drm_writeback.h
@@ -30,6 +30,8 @@ struct drm_writeback_connector {
 	 * @drm_writeback_connector control the behaviour of the @encoder
 	 * by passing the @enc_funcs parameter to drm_writeback_connector_init()
 	 * function.
+	 * For users of drm_writeback_connector_init_with_encoder(), this field
+	 * is not valid as the encoder is managed within their drivers.
 	 */
 	struct drm_encoder encoder;
 
@@ -153,6 +155,12 @@ int drm_writeback_connector_init(struct drm_device *dev,
 				 const u32 *formats, int n_formats,
 				 u32 possible_crtcs);
 
+int drm_writeback_connector_init_with_encoder(struct drm_device *dev,
+				struct drm_writeback_connector *wb_connector,
+				struct drm_encoder *enc,
+				const struct drm_connector_funcs *con_funcs, const u32 *formats,
+				int n_formats);
+
 int drm_writeback_set_fb(struct drm_connector_state *conn_state,
 			 struct drm_framebuffer *fb);