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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [SKL Bisected] eDP can not be lighted up after entering kernel"
href="https://bugs.freedesktop.org/show_bug.cgi?id=89554#c9">Comment # 9</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [SKL Bisected] eDP can not be lighted up after entering kernel"
href="https://bugs.freedesktop.org/show_bug.cgi?id=89554">bug 89554</a>
from <span class="vcard"><a class="email" href="mailto:sonika.jindal@intel.com" title="Sonika <sonika.jindal@intel.com>"> <span class="fn">Sonika</span></a>
</span></b>
<pre>(In reply to ye.tian from <a href="show_bug.cgi?id=89554#c6">comment #6</a>)
<span class="quote">> (In reply to Sonika from <a href="show_bug.cgi?id=89554#c2">comment #2</a>)
> > For me with kernel version 4.0.0-rc3, eDP is working fine.
> >
> > The EDP low vswing table gets selected only when edp_vswing_preemph is set
> > in vbt.
> > For me, it works with both low vswing table as well as the dp translation
> > table with an edp1.3 panel.
> >
> > Only thing I can suspect is that we are trying to use low vswing table for
> > some panel which is not able to handle those values.
> > Can you please see if this variable is set in vbt?
> > If it is set, please try to disable it and try.
>
> I have no idea, could you tell me how to set this variable? where?</span >
There should be one field in the eDP config in vbt VswingPreEmphasisValue.
Where it should be set to 0 for low vswing and 1 for default for the panel in
use:
0 = Low Power Swing setting(200 mV)
1 = Default Swing settings(400 mV)
If you have access to the code, you can try hardcoding
dev_priv->vbt.edp_low_vswing to false in parse_edp inside intel_bios.c to use
the default vswing values</pre>
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