[PATCH v7 2/6] drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence

From: Dmitry Osipenko
Date: Sun Jun 14 2020 - 13:23:31 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 presence of the local port in a device-tree
before proceeding with parsing the graph.

Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
drivers/gpu/drm/drm_of.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index b50b44e76279..e0652c38f357 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -239,13 +239,24 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
struct drm_bridge **bridge)
{
int ret = -EPROBE_DEFER;
- struct device_node *remote;
+ struct device_node *local, *remote;

if (!panel && !bridge)
return -EINVAL;
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 presence of the local port.
+ */
+ local = of_graph_get_local_port(np);
+ if (!local)
+ return -ENODEV;
+
+ of_node_put(local);
+
remote = of_graph_get_remote_node(np, port, endpoint);
if (!remote)
return -ENODEV;
--
2.26.0