[Bug 96569] system freezes during boot, [drm:intel_dp_start_link_train [i915]] and [drm:intel_psr_work [i915]] ERROR

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=96569

Ander Conselvan de Oliveira <conselvan2 at gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |conselvan2 at gmail.com

--- Comment #2 from Ander Conselvan de Oliveira <conselvan2 at gmail.com> ---
Created attachment 125056
  --> https://bugs.freedesktop.org/attachment.cgi?id=125056&action=edit
Workaround: don't retrain the link from long pulse

(In reply to Jani Nikula from comment #1)
> This is silly.
> 
> Based on the logs, I presume this happens before we enable eDP for the first
> time:
> 
> -> intel_dp_detect
> -> intel_dp_long_pulse
> -> intel_dp_check_link_status (since it's eDP, connector status remains
> connected)
> -> apparently the crtc is active, but the channel eq is not okay, because
> well, we've never trained before, and then we go on trying to retrain
> 
> Ander, any ideas when we caused this to happen?

Probably in the commit below. We had logic to retrain the link from long hpd,
and that series changed intel_dp_detect() to share code with the long pulse
handling. The problem is that the long pulse handling is also called from
output polling during boot and resume from suspend and ends up calling that.

I'm not sure what the proper fix would be, but the attached patch would confirm
that's the issue.

commit 7d23e3c37bb3fc6952dc84007ee60cb533fd2d5c
Author: Shubhangi Shrivastava <shubhangi.shrivastava at intel.com>
Date:   Wed Mar 30 18:05:23 2016 +0530

    drm/i915: Cleaning up intel_dp_hpd_pulse

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