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<base href="https://bugs.freedesktop.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Blank screen after locking and vt-switch"
href="https://bugs.freedesktop.org/show_bug.cgi?id=110863">110863</a>
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<th>Summary</th>
<td>Blank screen after locking and vt-switch
</td>
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>DRM/Intel
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>corsac@debian.org
</td>
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
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<p>
<div>
<pre>Hi,
I'm reporting a bug as the Debian maintainer of the Xfce desktop environment.
Since people have started to upgrade to future new stable version (Buster,
currently testing) I have had multiple bug reports with a similar behavior.
The locking infrastructure in Debian buster with Xfce relies on following
components:
- LightDM (the login screen manager) with its greeter, lightdm-gtk-greeter
- light-locker: the lock screen
light-locker works by drawing a simple window on top of the desktop on VT7 and
locking it, then doing a vt-switch to a new lightdm on VT8. When entering the
correct login/password on the login screen, a DBus message is sent to
light-locker which unlocks the screen.
Unfortunately, on setups with Intel adapters (of various generations, I
personnaly reproduced on a ThinkPad X250 with Broadwell and Thinkpad X230 with
Ivy Bridge) when the screen is then shut down (for power saving or because of a
suspend), the screen doesn't turn back on when moving the mouse or entering
keys.
As far as I can tell the only way to bring back the screen is to manually
switch VT (with ctrl-alt-Fx).
There's a downtream bug report at
<a href="https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=805711">https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=805711</a> but unfortunately
there's a lot of noise so I'm a bit lost myself.
There's an upstream bug report on Light Locker
(<a href="https://github.com/the-cavalry/light-locker/issues/108">https://github.com/the-cavalry/light-locker/issues/108</a>) but it doesn't seem
completely related.
uname -m: x86_64 (but I guess i386 is affected as well)
uname -r: 4.19.0-4-amd64
Linux Distribution: Debian testing/sid
Machine: at least ThinkPads X230 and X250 for me but Debian bug report shows a
lot more
Display connector: LVDS, eDP, DP (and I guess HDMI, VGA...)
- DDX is modesetting from Xorg core
If you want more specific information please ask. I know the issue is weird.
It's likely a bad interaction between various components (i915, DDX) and a
not-often used codepath (vt-switch + DPMS maybe?)</pre>
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</p>
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