From 082ed61dabbc3540e0dc4180fc547b23e6cc637d Mon Sep 17 00:00:00 2001
From: Aurabindo Pillai <aurabindo.pillai@amd.com>
Date: Fri, 8 Oct 2021 16:07:45 -0400
Subject: [PATCH] drm/amd/display: fix null pointer deref when plugging in display
Git-commit: 1f3b22e4eb162e0b1d423106a47484943a22a309
Patch-mainline: v5.16-rc1
References: stable-5.14.19

[ Upstream commit 1f3b22e4eb162e0b1d423106a47484943a22a309 ]

[Why&How]
When system boots in headless mode, connecting a 4k display creates a
null pointer dereference due to hubp for a certain plane being null.
Add a condition to check for null hubp before dereferencing it.

Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
index fafed1e4a998..0950784bafa4 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
@@ -1002,7 +1002,8 @@ void dcn30_set_disp_pattern_generator(const struct dc *dc,
 		/* turning off DPG */
 		pipe_ctx->plane_res.hubp->funcs->set_blank(pipe_ctx->plane_res.hubp, false);
 		for (mpcc_pipe = pipe_ctx->bottom_pipe; mpcc_pipe; mpcc_pipe = mpcc_pipe->bottom_pipe)
-			mpcc_pipe->plane_res.hubp->funcs->set_blank(mpcc_pipe->plane_res.hubp, false);
+			if (mpcc_pipe->plane_res.hubp)
+				mpcc_pipe->plane_res.hubp->funcs->set_blank(mpcc_pipe->plane_res.hubp, false);
 
 		stream_res->opp->funcs->opp_set_disp_pattern_generator(stream_res->opp, test_pattern, color_space,
 				color_depth, solid_color, width, height, offset);
-- 
2.26.2