drm/amd/display: Check dce_hwseq before dereferencing it

commit b669507b637eb6b1aaecf347f193efccc65d756e upstream.

[WHAT]

hws was checked for null earlier in dce110_blank_stream, indicating hws
can be null, and should be checked whenever it is used.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 79db43611ff61280b6de58ce1305e0b2ecf675ad)
Cc: stable@vger.kernel.org
Signed-off-by: Rahul Sharma <black.hawk@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
index 0172fede51b5bcfd50912a47f40c486ca6d47858..14f5b4f00f724fab8f73ca48ac90b07152e2cc5b 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
@@ -1228,7 +1228,7 @@ void dce110_blank_stream(struct pipe_ctx *pipe_ctx)
        struct dce_hwseq *hws = link->dc->hwseq;
 
        if (link->local_sink && link->local_sink->sink_signal == SIGNAL_TYPE_EDP) {
-               if (!link->skip_implict_edp_power_control)
+               if (!link->skip_implict_edp_power_control && hws)
                        hws->funcs.edp_backlight_control(link, false);
                link->dc->hwss.set_abm_immediate_disable(pipe_ctx);
        }