drm/amd/display: check dc_link before dereferencing

drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:6683 amdgpu_dm_connector_funcs_force()
warn: variable dereferenced before check 'dc_link' (see line 6663)

Fixes: 967176179215 ("drm/amd/display: fix null-pointer dereference on edid reading")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 32efce81a5a7473949da0e7bc9e6724a584413fd..46dd06e8fc7e127dbaa0d7c8c96632c7972b901a 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6653,7 +6653,7 @@ static void amdgpu_dm_connector_funcs_force(struct drm_connector *connector)
        struct edid *edid;
        struct i2c_adapter *ddc;
 
-       if (dc_link->aux_mode)
+       if (dc_link && dc_link->aux_mode)
                ddc = &aconnector->dm_dp_aux.aux.ddc;
        else
                ddc = &aconnector->i2c->base;