drm_of_find_panel_or_bridge() is widely used, but many callers pass NULL into the @panel or the @bridge arguments, thus making a very partial usage of this rather complex function.
Besides, the bridge returned in @bridge is not refcounted, thus making this API unsafe when DRM bridge hotplug will be introduced. Solve both issues for the cases of calls to drm_of_find_panel_or_bridge() with a NULL @panel pointer by adding a new function that only looks for bridges (and is thus much simpler) and increments the refcount of the returned bridge. The new function is identical to drm_of_find_panel_or_bridge() except it: - handles bridge refcounting: uses of_drm_find_and_get_bridge() instead of of_drm_find_bridge() internally to return a refcounted bridge - is simpler to use: just takes no @panel parameter, returns the pointer in the return value instead of a double pointer argument - has a simpler implementation: it is equal to drm_of_find_panel_or_bridge() after removing the code that becomes dead when @panel == NULL Also add this function to drm_bridge.c and not drm_of.c because it returns bridges only. Reviewed-by: Dmitry Baryshkov <[email protected]> Reviewed-by: Laurent Pinchart <[email protected]> Signed-off-by: Luca Ceresoli <[email protected]> --- Changes in v5: - add missing ERR_PTR() in return statement for no-OF inline variant Changes in v4: - update function declaration in non-OF case - fix grammar in comment Changes in v2: - return the bridge in the return value, not a double pointer --- drivers/gpu/drm/drm_bridge.c | 41 +++++++++++++++++++++++++++++++++++++++++ include/drm/drm_bridge.h | 7 +++++++ 2 files changed, 48 insertions(+) diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index b46c01db8d83..687b36eea0c7 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -1582,6 +1582,47 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np) return bridge; } EXPORT_SYMBOL(of_drm_find_bridge); + +/** + * of_drm_get_bridge_by_endpoint - return DRM bridge connected to a port/endpoint + * @np: device tree node containing output ports + * @port: port in the device tree node, or -1 for the first port found + * @endpoint: endpoint in the device tree node, or -1 for the first endpoint found + * + * Given a DT node's port and endpoint number, find the connected node and + * return the associated drm_bridge device. + * + * The refcount of the returned bridge is incremented. Use drm_bridge_put() + * when done with it. + * + * Returns a pointer to the connected drm_bridge, or a negative error on failure + */ +struct drm_bridge *of_drm_get_bridge_by_endpoint(const struct device_node *np, + int port, int endpoint) +{ + struct drm_bridge *bridge; + + /* + * of_graph_get_remote_node() produces a noisy error message if port + * node isn't found and the absence of the port is a legit case here, + * so at first we silently check whether graph is present in the + * device-tree node. + */ + if (!of_graph_is_present(np)) + return ERR_PTR(-ENODEV); + + struct device_node *remote __free(device_node) = + of_graph_get_remote_node(np, port, endpoint); + if (!remote) + return ERR_PTR(-ENODEV); + + bridge = of_drm_find_and_get_bridge(remote); + if (!bridge) + return ERR_PTR(-EPROBE_DEFER); + + return bridge; +} +EXPORT_SYMBOL_GPL(of_drm_get_bridge_by_endpoint); #endif /** diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index fdac9a526f38..4ba3a5deef9a 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -1327,6 +1327,8 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge, #ifdef CONFIG_OF struct drm_bridge *of_drm_find_and_get_bridge(struct device_node *np); struct drm_bridge *of_drm_find_bridge(struct device_node *np); +struct drm_bridge *of_drm_get_bridge_by_endpoint(const struct device_node *np, + int port, int endpoint); #else static inline struct drm_bridge *of_drm_find_and_get_bridge(struct device_node *np) { @@ -1336,6 +1338,11 @@ static inline struct drm_bridge *of_drm_find_bridge(struct device_node *np) { return NULL; } +static inline struct drm_bridge *of_drm_get_bridge_by_endpoint(const struct device_node *np, + int port, int endpoint) +{ + return ERR_PTR(-ENODEV); +} #endif static inline bool drm_bridge_is_last(struct drm_bridge *bridge) -- 2.54.0
