drm/radeon: don't probe MST on hw we don't support it on

If you do radeon.mst=1 on a gpu without mst hw, and then
plug some mst hw it will oops instead of falling back.

So check we have DCE5 at least before proceeding.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_dp_mst.c b/drivers/gpu/drm/radeon/radeon_dp_mst.c
index 2b98ed3e684d..257b10be5cda 100644
--- a/drivers/gpu/drm/radeon/radeon_dp_mst.c
+++ b/drivers/gpu/drm/radeon/radeon_dp_mst.c
@@ -663,12 +663,17 @@ int
 radeon_dp_mst_probe(struct radeon_connector *radeon_connector)
 {
         struct radeon_connector_atom_dig *dig_connector = radeon_connector->con_priv;
+        struct drm_device *dev = radeon_connector->base.dev;
+        struct radeon_device *rdev = dev->dev_private;
         int ret;
         u8 msg[1];
 
         if (!radeon_mst)
                 return 0;
 
+        if (!ASIC_IS_DCE5(rdev))
+                return 0;
+
         if (dig_connector->dpcd[DP_DPCD_REV] < 0x12)
                 return 0;