[Bug 109398] booting gives black screen [drm:intel_dp_start_link_train] [CONNECTOR:67:eDP-1] Link Training failed at link rate = 162000, lane count = 2

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=109398

Jani Nikula <jani.nikula at intel.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |NEEDINFO

--- Comment #7 from Jani Nikula <jani.nikula at intel.com> ---
Regression of a fix to another regression, makes your head explode.

When we started to handle clock recovery failures on link training, we knew
there were eDP panels out there that failed the initial clock recovery but
passed it in the channel equalization phase. We no longer have that failure
path within channel equalization.

We failed to root cause the original problem, and added two layers of duct tape
on top. So here we are.

---

Please try reverting *both*

1e712535c51a ("drm/i915/dp: Link train Fallback on eDP only if fallback link BW
can fit panel's native mode")

and

c0cfb10d9e1d ("drm/i915/edp: Do not do link training fallback or prune modes on
EDP")

How does that work?

Please do *not* use the i915.fastboot parameter for any further testing.

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