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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - Display Port BYT-M [N2807] - Data link training fails sporadically"
href="https://bugs.freedesktop.org/show_bug.cgi?id=93956#c3">Comment # 3</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - Display Port BYT-M [N2807] - Data link training fails sporadically"
href="https://bugs.freedesktop.org/show_bug.cgi?id=93956">bug 93956</a>
from <span class="vcard"><a class="email" href="mailto:werner.zeh@gmx.net" title="werner.zeh@gmx.net">werner.zeh@gmx.net</a>
</span></b>
<pre>Hi.
I have checked our kernel, which is version 4.2.0.16.
The mentioned patch is already in that kernel which shows the display port link
training issue.
To me, it seems like the PHY of display port links is not running properly.
This is indicated by DPLLA_CTRL-Reg, where the lower byte holds the phy status
for both ports. As it seems not to happen with GOP+UEFI, maybe some registers
are initialized in a different way using the kernel driver.
And I just want to highlight that this error happens only on few boards, not on
every. And these boards are affected shows a temperature dependency: the error
is more likely to happen when SoC is cold.</pre>
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