Re: [PATCH] Revert "drm/i915: Implement Link Rate fallback on Link training failure"

Jani Nikula
2017-03-01T17:35:21Z

On Wed, 01 Mar 2017, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> On Wed, Mar 01, 2017 at 06:17:49PM +0100, Daniel Vetter wrote:
>> This reverts commit 233ce881dd91fb13eb6b09deefae33168e6ead4c.
>>
>> I assumed it's ok, but really should have double-checked - CI caught
>> tons of fail :(

Considering the velocity of drm-tip, I think any CI results for patches
have a rather limited best before date. The patch should've been resent
and gone through testing again before merging.

> For the record, the failure comes from the error message in
> intel_dp_get_link_train_fallback_values() as take the fallback path. As
> userspace is informed, we don't need an *ERROR* at that point.
>
> The really interesting question is why we are seeing link-training
> failures in CI at all, and whether igt should be checking and reporting
> link-status=BAD.

It's possible (I didn't check the logs) this pertains to the failure
mode I've sometimes seen, where clock recovery fails, but as we continue
with channel equalization anyway (without this patch), everything
succeeds there. At worst we need to root cause and fix that issue
first. :(

BR,
Jani.

--
Jani Nikula, Intel Open Source Technology Center