[PATCH v6 10/26] drm/bridge: add devm_drm_of_get_bridge_by_node()

[Luca Ceresoli]

devm_drm_of_get_bridge(), which is based on graph links, is the recommended
function to get a pointer to the following bridge.

This is valid even for panels, for which the recommended device tree
description is via graph links and not (or not only) panel subnodes of a
panel controller (e.g. "dsi@1234" controller node with a "panel@0"
subnode).

However there are drivers supporting the panel subnode description in
addition to the graph links. For those drivers add a _by_node variant that
takes the node of the target node.

Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Signed-off-by: Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx>

---

This patch was added in v6.
---
 drivers/gpu/drm/drm_bridge.c | 30 ++++++++++++++++++++++++++++++
 include/drm/drm_bridge.h     |  8 ++++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 2aa17fbe538b86066c4e68f0d0e8046e9ca9b965..b0834b8644284e5f7751cec81724af849b4180e7 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -1407,6 +1407,36 @@ struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
 }
 EXPORT_SYMBOL(devm_drm_of_get_bridge);
 
+/**
+ * devm_drm_of_get_bridge_by_node - Return bridge for a given OF node
+ * @dev: device to tie the bridge lifetime to
+ * @bridge_node: device node of the remote bridge
+ *
+ * Given a bridge DT node, returns the associated bridge if any. This
+ * should be used in addition to devm_drm_of_get_bridge() when the regular
+ * graph link search is not enough, e.g. for drivers that need to support
+ * panels described only as subnodes.
+ *
+ * RETURNS:
+ * A pointer to the bridge if successful, or an error pointer otherwise.
+ */
+struct drm_bridge *devm_drm_of_get_bridge_by_node(struct device *dev,
+						  struct device_node *bridge_node)
+{
+	struct drm_bridge *bridge;
+	int ret;
+
+	if (!bridge_node)
+		return ERR_PTR(-EINVAL);
+
+	bridge = of_drm_find_bridge(bridge_node);
+	if (!bridge)
+		return ERR_PTR(-ENODEV);
+
+	return bridge;
+}
+EXPORT_SYMBOL(devm_drm_of_get_bridge_by_node);
+
 /**
  * drmm_of_get_bridge - Return next bridge in the chain
  * @drm: device to tie the bridge lifetime to
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 496dbbd2ad7edff7f091adfbe62de1e33ef0cf07..1561347c4991dac6022319774510f9560c9283c3 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1088,6 +1088,8 @@ static inline int drm_panel_bridge_set_orientation(struct drm_connector *connect
 #if defined(CONFIG_OF) && defined(CONFIG_DRM_PANEL_BRIDGE)
 struct drm_bridge *devm_drm_of_get_bridge(struct device *dev, struct device_node *node,
 					  u32 port, u32 endpoint);
+struct drm_bridge *devm_drm_of_get_bridge_by_node(struct device *dev,
+						  struct device_node *bridge_node);
 struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm, struct device_node *node,
 					  u32 port, u32 endpoint);
 #else
@@ -1099,6 +1101,12 @@ static inline struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
 	return ERR_PTR(-ENODEV);
 }
 
+static inline struct drm_bridge *devm_drm_of_get_bridge_by_node(struct device *dev,
+								struct device_node *bridge_node)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
 						     struct device_node *node,
 						     u32 port,

-- 
2.34.1