[PATCH v7 02/12] drm: bridge: panel: Implement drmm_of_dsi_get_bridge helper

[Jagan Teki]

Implement a DRM-managed action helper that returns the next DSI bridge
in the chain.

Unlike general bridge return helper drmm_of_get_bridge, this helper
uses the dsi specific panel_or_bridge helper to find the next DSI
device in the pipeline.

Helper lookup a given downstream DSI device that has been added via
child or OF-graph port or ports node.

Upstream DSI looks for downstream devices using drm pointer, port and
endpoint number. Downstream devices added via child node don't affect
the port and endpoint number arguments.

Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
---
Changes for v7:
- new patch

 drivers/gpu/drm/bridge/panel.c | 34 ++++++++++++++++++++++++++++++++++
 include/drm/drm_bridge.h       | 10 ++++++++++
 2 files changed, 44 insertions(+)

diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
index d4b112911a99..d047c7d9551d 100644
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -501,4 +501,38 @@ struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
 }
 EXPORT_SYMBOL(drmm_of_get_bridge);
 
+/**
+ * drmm_of_dsi_get_bridge - Return next DSI bridge in the chain
+ * @drm: device to tie the bridge lifetime to
+ * @np: device tree node containing DSI output ports
+ * @port: port in the device tree node
+ * @endpoint: endpoint in the device tree node
+ *
+ * Given a DT node's port and endpoint number, finds the connected node
+ * and returns the associated DSI bridge if any, or creates and returns
+ * a DSI panel bridge instance if a panel is connected.
+ *
+ * Returns a drmm managed pointer to the DSI bridge if successful, or
+ * an error pointer otherwise.
+ */
+struct drm_bridge *drmm_of_dsi_get_bridge(struct drm_device *drm,
+					  struct device_node *np,
+					  u32 port, u32 endpoint)
+{
+	struct drm_bridge *bridge;
+	struct drm_panel *panel;
+	int ret;
+
+	ret = drm_of_dsi_find_panel_or_bridge(np, port, endpoint,
+					      &panel, &bridge);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (panel)
+		bridge = drmm_panel_bridge_add(drm, panel);
+
+	return bridge;
+}
+EXPORT_SYMBOL(drmm_of_dsi_get_bridge);
+
 #endif
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 42f86327b40a..a1a31704b917 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -931,6 +931,9 @@ struct drm_bridge *devm_drm_of_get_bridge(struct device *dev, struct device_node
 					  u32 port, u32 endpoint);
 struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm, struct device_node *node,
 					  u32 port, u32 endpoint);
+struct drm_bridge *drmm_of_dsi_get_bridge(struct drm_device *drm,
+					  struct device_node *node,
+					  u32 port, u32 endpoint);
 #else
 static inline struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
 							struct device_node *node,
@@ -947,6 +950,13 @@ static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
 {
 	return ERR_PTR(-ENODEV);
 }
+
+static inline struct drm_bridge *drmm_of_dsi_get_bridge(struct drm_device *drm,
+							struct device_node *node,
+							u32 port, u32 endpoint)
+{
+	return ERR_PTR(-ENODEV);
+}
 #endif
 
 #endif
-- 
2.25.1