[PATCH v8 2/7] drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence

From: Dmitry Osipenko
Date: Wed Jun 17 2020 - 18:28:04 EST


When graph isn't defined in a device-tree, the of_graph_get_remote_node()
prints a noisy error message, telling that port node is not found. This is
undesirable behaviour in our case because absence of a panel/bridge graph
is a valid case. Let's check the graph's presence in a device-tree before
proceeding with parsing of the graph.

Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
drivers/gpu/drm/drm_of.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index b50b44e76279..cbe65efdae39 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -246,6 +246,15 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
if (panel)
*panel = NULL;

+ /*
+ * 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 presents in the
+ * device-tree node.
+ */
+ if (!of_graph_presents(np))
+ return -ENODEV;
+
remote = of_graph_get_remote_node(np, port, endpoint);
if (!remote)
return -ENODEV;
--
2.26.0