[Bug 101144] [BAT][SKL] *ERROR* failed to enable link training

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=101144

--- Comment #21 from Marta Löfstedt <marta.lofstedt at intel.com> ---
(In reply to Ville Syrjala from comment #16)
> One peculiar thing see in some of the logs at least is a double long HPD
> when we turn on the panel. I wonder if there's some kind of transient glitch
> on the VDD line or something that causes to panel to do some kind of
> off->on->off->on transition.
> 
> To get some more debug information maybe someone could hack up a test patch
> that checks the state of the HPD pin in a few places during the modeset; Eg.
> just after the panel supposedly powered on and just before starting link
> training, and maybe in a few places in between.
> 
> What kind of machine is this? I'm wondering of the panel power delays might
> be off somehow, eg. the power cycle delay might be too short and the panel
> doesn't like it if we power it back up too soon...

Ville, I have looked through a lot of the dmesg and this double long HPD thing
appear to always happen before we get the aux timeout and after that the link
training dmesg-warn (and after that the bug 101167 issue), actually I have even
seen 3 long HPDs in a short time.

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