[PATCH] drm/amd/display: Fix crash in hwss_set_output_transfer_func()

["Timur Kristóf" <timur.kristof@gmail.com>]

The pipe_ctx->plane_res.hubp pointer is NULL on all DCE
hardware, which causes a kernel NULL pointer dereference
on all Vega and older GPUs.

Let's add a simple NULL check.

Fixes: f879f53407f0 ("drm/amd/display: Refactor DPP_SET_OUTPUT_TRANSFER_FUNC to drop pipe_ctx")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Cc: Tomasz Siemek <tomasz.siemek@amd.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_hw_sequencer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/core/dc_hw_sequencer.c
index 11411fa94665..5495e493b2eb 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_hw_sequencer.c
@@ -1900,7 +1900,8 @@ void hwss_set_output_transfer_func(struct dc *dc, struct pipe_ctx *pipe_ctx)
 				.xfm = pipe_ctx->plane_res.xfm,
 				.dpp = pipe_ctx->plane_res.dpp,
 				.mpc = dc->res_pool->mpc,
-				.mpcc_id = pipe_ctx->plane_res.hubp->inst,
+				.mpcc_id = pipe_ctx->plane_res.hubp ?
+						pipe_ctx->plane_res.hubp->inst : 0,
 				.is_top_pipe = resource_is_pipe_type(pipe_ctx, OPP_HEAD),
 				.stream = pipe_ctx->stream,
 			}
-- 
2.55.0