[PATCH] drm/tegra: dsi: Add missing check for of_find_device_by_node

[Chen Ni]

Add check for the return value of of_find_device_by_node() and return
the error if it fails in order to avoid NULL pointer dereference.

Fixes: e94236cde4d5 ("drm/tegra: dsi: Add ganged mode support")
Signed-off-by: Chen Ni <nichen at iscas.ac.cn>
---
 drivers/gpu/drm/tegra/dsi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tegra/dsi.c b/drivers/gpu/drm/tegra/dsi.c
index a9870c828374..4101b2e01211 100644
--- a/drivers/gpu/drm/tegra/dsi.c
+++ b/drivers/gpu/drm/tegra/dsi.c
@@ -1543,9 +1543,11 @@ static int tegra_dsi_ganged_probe(struct tegra_dsi *dsi)
 	np = of_parse_phandle(dsi->dev->of_node, "nvidia,ganged-mode", 0);
 	if (np) {
 		struct platform_device *gangster = of_find_device_by_node(np);
+		of_node_put(np);
+		if (!gangster)
+			return -EPROBE_DEFER;
 
 		dsi->slave = platform_get_drvdata(gangster);
-		of_node_put(np);
 
 		if (!dsi->slave) {
 			put_device(&gangster->dev);
-- 
2.25.1