<html>
<head>
<base href="https://bugs.freedesktop.org/">
</head>
<body>
<p>
<div>
<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - [SKL] DPCD backlight causes black screen on ThinkPad X1 Carbon 4th Gen"
href="https://bugs.freedesktop.org/show_bug.cgi?id=101619#c11">Comment # 11</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - [SKL] DPCD backlight causes black screen on ThinkPad X1 Carbon 4th Gen"
href="https://bugs.freedesktop.org/show_bug.cgi?id=101619">bug 101619</a>
from <span class="vcard"><a class="email" href="mailto:david.weinehall@intel.com" title="David Weinehall <david.weinehall@intel.com>"> <span class="fn">David Weinehall</span></a>
</span></b>
<pre>It seems that the issue is with DBC rather than DPCD backlight as I first
thought; reverting the DBC patch (or disabling dbc) seems to be enough to get
things working.
Setting min=100, max=100 didn't solve anything, neither did min=40, max=60
(just in case the display has some weird hangup about 100%).
The patch that introduces the issue is:
ae25eceab616d16a07bcaa434b84463d58a3bdc3
On a somewhat tangential note, having DBC enabled by default feels very
dubious, in my opinion, especially since it's not a user adjustable option. If
there's no way to toggle DBC on/off from userspace I much rather adjust the
brightness using Fn + F5/F6 than have the system decide what's best for me.
This of course only applies if it's a strict choice between DBC & manual
control; if the DBC only adjust the brightness already set by the user, then
it's a different story, obviously.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
<li>You are the assignee for the bug.</li>
<li>You are the QA Contact for the bug.</li>
</ul>
</body>
</html>