[Bug 106223] [KBL-R] DP link training failures lead to downgraded link parameters and resolution

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=106223

--- Comment #22 from Ricardo Ribalda <ricardo.ribalda at gmail.com> ---
(In reply to Clinton Taylor from comment #21)
> This issue could also manifest if link training is being attempted before
> the USB-C Hub is ready to accept a signal. A small delay before attempting
> Link Training with a USB-C LSPCON may work.
> 
> Ricardo,
>    Could you try adding a short delay msleep (200) to the start of
> intel_dp_start_link_train() and see if your retries drops to 0?

That did not do the trick :(, also it does not explain why I got a couple of
times more than one retries.

@@ -317,10 +317,18 @@ void
 intel_dp_start_link_train(struct intel_dp *intel_dp)
 {
        struct intel_connector *intel_connector = intel_dp->attached_connector;
+       int tries;

-       if (!intel_dp_link_training_clock_recovery(intel_dp))
-               goto failure_handling;
-       if (!intel_dp_link_training_channel_equalization(intel_dp))
+       msleep(200);
+
+       for (tries = 0; tries < 5; tries++) {
+               if (!intel_dp_link_training_clock_recovery(intel_dp))
+                       continue;
+               if (intel_dp_link_training_channel_equalization(intel_dp))
+                       break;
+       }
+
+       if (tries == 5)
                goto failure_handling;

        DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Link Training Passed at Link Rate =
%d, Lane count = %d",

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