[PATCH 2/4] drm/of: add support to find any enabled endpoint

[Rob Clark <robdclark@gmail.com>]

From: Rob Clark <robdclark@chromium.org>

To handle the case where there are multiple panel endpoints, only one of
which is enabled/installed, add support for a wildcard endpoint value to
request finding whichever endpoint is enabled.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/drm_of.c | 41 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index 0ca58803ba46..2baf44e401b8 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -219,11 +219,44 @@ int drm_of_encoder_active_endpoint(struct device_node *node,
 }
 EXPORT_SYMBOL_GPL(drm_of_encoder_active_endpoint);
 
+static int find_enabled_endpoint(const struct device_node *node, u32 port)
+{
+	struct device_node *endpoint_node, *remote;
+	u32 endpoint = 0;
+
+	for (endpoint = 0; ; endpoint++) {
+		endpoint_node = of_graph_get_endpoint_by_regs(node, port, endpoint);
+		if (!endpoint_node) {
+			pr_debug("No more endpoints!\n");
+			return -ENODEV;
+		}
+
+		remote = of_graph_get_remote_port_parent(endpoint_node);
+		of_node_put(endpoint_node);
+		if (!remote) {
+			pr_debug("no valid remote node\n");
+			continue;
+		}
+
+		if (!of_device_is_available(remote)) {
+			pr_debug("not available for remote node\n");
+			of_node_put(remote);
+			continue;
+		}
+
+		pr_debug("found enabled endpoint %d for %s\n", endpoint, remote->name);
+		of_node_put(remote);
+		return endpoint;
+	}
+
+	return -ENODEV;
+}
+
 /**
  * drm_of_find_panel_or_bridge - return connected panel or bridge device
  * @np: device tree node containing encoder output ports
  * @port: port in the device tree node
- * @endpoint: endpoint in the device tree node
+ * @endpoint: endpoint in the device tree node, or -1 to find an enabled endpoint
  * @panel: pointer to hold returned drm_panel
  * @bridge: pointer to hold returned drm_bridge
  *
@@ -246,6 +279,12 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 	if (panel)
 		*panel = NULL;
 
+	if (endpoint == -1) {
+		endpoint = find_enabled_endpoint(np, port);
+		if (endpoint < 0)
+			return endpoint;
+	}
+
 	remote = of_graph_get_remote_node(np, port, endpoint);
 	if (!remote)
 		return -ENODEV;
-- 
2.23.0