[PATCH] drm/amd/display: fix null pointer deref when plugging in display

[Aurabindo Pillai]

[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 at amd.com>
---
 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 01a90badd173..2936a334cd64 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
@@ -969,7 +969,8 @@ 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);
-- 
2.30.2