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

[Dave Airlie]

From: Dave Airlie <airl...@redhat.com>

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 at redhat.com>
---
 drivers/gpu/drm/radeon/radeon_dp_mst.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_dp_mst.c 
b/drivers/gpu/drm/radeon/radeon_dp_mst.c
index 2b98ed3..257b10be 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;

-- 
2.4.2