From: Shirish S <shirish.s@amd.com>
Date: Thu, 15 Mar 2018 16:01:00 +0530
Subject: drm/amd/display: fix dereferencing possible ERR_PTR()
Git-commit: cd2d6c92a8e39d7e50a5af9fcc67d07e6a89e91d
Patch-mainline: v4.16-rc7
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

This patch fixes static checker warning caused by
"36cc549d5986: "drm/amd/display: disable CRTCs with
NULL FB on their primary plane (V2)"

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Shirish S <shirish.s@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4778,6 +4778,9 @@ static int dm_atomic_check_plane_state_f
 			return -EDEADLK;
 
 		crtc_state = drm_atomic_get_crtc_state(plane_state->state, crtc);
+		if (IS_ERR(crtc_state))
+			return PTR_ERR(crtc_state);
+
 		if (crtc->primary == plane && crtc_state->active) {
 			if (!plane_state->fb)
 				return -EINVAL;