[PATCH 7.1 397/438] drm/amd/display: check if dml21_add_phantom_plane() is successful

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alex Deucher <[email protected]>

commit 000acb4ce7fb9feba3072ce468ad681f6585cd5d upstream.

Verify that the phantom plane was allocated to avoid a later
segfault.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4970
Fixes: 70839da63605 ("drm/amd/display: Add new DCN401 sources")
Reviewed-by: Dillon Varone <[email protected]>
Signed-off-by: Fangzhi Zuo <[email protected]>
Tested-by: Dan Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
(cherry picked from commit 5adb54abe5a8e82cbff7f8806db30a5f4924329f)
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/gpu/drm/amd/display/dc/dml2_0/dml21/dml21_utils.c |   15 ++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/dml21_utils.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2_0/dml21/dml21_utils.c
@@ -359,14 +359,13 @@ void dml21_handle_phantom_streams_planes
 					main_plane = main_stream_status->plane_states[dc_plane_index];
 
 					/* create phantom planes for subvp enabled plane */
-					dml21_add_phantom_plane(dml_ctx,
-							dc,
-							context,
-							phantom_stream,
-							main_plane,
-							&dml_ctx->v21.mode_programming.programming->plane_programming[dml_plane_index]);
-
-					phantoms_added = true;
+					if (dml21_add_phantom_plane(dml_ctx,
+								    dc,
+								    context,
+								    phantom_stream,
+								    main_plane,
+								    &dml_ctx->v21.mode_programming.programming->plane_programming[dml_plane_index]))
+						phantoms_added = true;
 				}
 			}
 		}