drm/amd/display: System Hang When System enters to S0i3 w/ iGPU

[why]
System Hang when system enters to S0i3 w/ iGPU
some link_enc are NULL due to BIOS integration info table not correct,
but driver should have enough null pointer protection.

Reviewed-by: Leo Chen <leo.chen@amd.com>
Signed-off-by: Charlene Liu <Charlene.Liu@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Signed-off-by: Chuanyu Tseng <Chuanyu.Tseng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn42/dcn42_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn42/dcn42_hwseq.c
index 8e12dc1297c4d3330751fc662bd27253d55b556c..7bf94eae30a6fd403eb3bac06a153561e2e76e76 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn42/dcn42_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn42/dcn42_hwseq.c
@@ -203,7 +203,8 @@ void dcn42_init_hw(struct dc *dc)
                        for (i = 0; i < dc->link_count; i++) {
                                struct dc_link *link = dc->links[i];
 
-                               if (link->link_enc->funcs->is_dig_enabled &&
+                               if (link && link->link_enc &&
+                                       link->link_enc->funcs->is_dig_enabled &&
                                                link->link_enc->funcs->is_dig_enabled(link->link_enc) &&
                                                hws->funcs.power_down) {
                                        hws->funcs.power_down(dc);