drm/i915/dp: read more receiver capability bits on hotplug

When a hotplug event is received, we need to check the receiver cap bits
in case they've changed (as they might with a hub or chain config).

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index fc51730b89d6..a9a5051419df 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1522,6 +1522,8 @@ intel_dp_link_down(struct intel_dp *intel_dp)
 static void
 intel_dp_check_link_status(struct intel_dp *intel_dp)
 {
+        int ret;
+
         if (!intel_dp->base.base.crtc)
                 return;
 
@@ -1530,6 +1532,15 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
                 return;
         }
 
+        /* Try to read receiver status if the link appears to be up */
+        ret = intel_dp_aux_native_read(intel_dp,
+                                       0x000, intel_dp->dpcd,
+                                       sizeof (intel_dp->dpcd));
+        if (ret != sizeof(intel_dp->dpcd)) {
+                intel_dp_link_down(intel_dp);
+                return;
+        }
+
         if (!intel_channel_eq_ok(intel_dp)) {
                 intel_dp_start_link_train(intel_dp);
                 intel_dp_complete_link_train(intel_dp);