[PATCH] drm/panel: check failure cases in the probe func

[Navid Emamdoost]

The following function calls may fail and return NULL, so the null check
is added.
of_graph_get_next_endpoint
of_graph_get_remote_port_parent
of_graph_get_remote_port

Signed-off-by: Navid Emamdoost <navid.emamdo...@gmail.com>
---
 drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c 
b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 28c0620dfe0f..9484fdb60f68 100644
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -399,7 +399,13 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
 
        /* Look up the DSI host.  It needs to probe before we do. */
        endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+       if (!endpoint)
+               return -ENODEV;
+
        dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+       if (!dsi_host_node)
+               return -ENODEV;
+
        host = of_find_mipi_dsi_host_by_node(dsi_host_node);
        of_node_put(dsi_host_node);
        if (!host) {
@@ -408,6 +414,9 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
        }
 
        info.node = of_graph_get_remote_port(endpoint);
+       if (!info.node)
+               return -ENODEV;
+
        of_node_put(endpoint);
 
        ts->dsi = mipi_dsi_device_register_full(host, &info);
-- 
2.17.1