From 893978f1b4d11753fc77d5bdaef1f4ff86696b8d Mon Sep 17 00:00:00 2001
From: Wesley Chalmers <wesley.chalmers@amd.com>
Date: Wed, 21 Jun 2023 19:13:26 -0400
Subject: [PATCH] drm/amd/display: Fix a bug when searching for
 insert_above_mpcc

commit 3d028d5d60d516c536de1ddd3ebf3d55f3f8983b upstream.

[WHY]
Currently, when insert_plane is called with insert_above_mpcc
parameter that is equal to tree->opp_list, the function returns NULL.

[HOW]
Instead, the function should insert the plane at the top of the tree.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jun Lei <jun.lei@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Wesley Chalmers <wesley.chalmers@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c
index 8192f1967e924..d3681db36c30b 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c
@@ -207,8 +207,9 @@ struct mpcc *mpc1_insert_plane(
 		/* check insert_above_mpcc exist in tree->opp_list */
 		struct mpcc *temp_mpcc = tree->opp_list;
 
-		while (temp_mpcc && temp_mpcc->mpcc_bot != insert_above_mpcc)
-			temp_mpcc = temp_mpcc->mpcc_bot;
+		if (temp_mpcc != insert_above_mpcc)
+			while (temp_mpcc && temp_mpcc->mpcc_bot != insert_above_mpcc)
+				temp_mpcc = temp_mpcc->mpcc_bot;
 		if (temp_mpcc == NULL)
 			return NULL;
 	}