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Screen is totally blank after sleep/lock

Graphical Environments, Managers, Multimedia & Desktop questions.
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micon
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Joined: 2018-04-13 19:54

Screen is totally blank after sleep/lock

#1 Post by micon »

I have a new computer running Debian 9 and xfce4 using lightdm. The trouble I'm having is that after the machine sleeps and the session is locked, the screen is blank and the login screen will not display.
I can switch to the character console (Ctl-Alt-F1) and the terminal displays fine. If I switch back to the X console (Alt-F7) a notice appears about the locked session, but then goes blank when it should be displaying the login screen.

xfce4: Version: 4.12.3
lightdm: Version: 1.18.3-1
nvidia drivers: NVIDIA-SMI 375.82 Driver Version: 375.82
OS: 4.9.0-5-amd64 #1 SMP Debian 4.9.65-3+deb9u2 (2018-01-04) x86_64 GNU/Linux

(Display is connected to built-in device via DisplayPort, not the NVIDIA GPU):
$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Device 5912 (rev 04)
01:00.0 VGA compatible controller: NVIDIA Corporation GP106 [GeForce GTX 1060 6GB] (rev a1)

I haven't been able to find any settings under xfce4 or anywhere else to remedy this. I'm happy to provide any other information you need to be able to help me diagnose this issue. Thanks!

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Meow
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Re: Screen is totally blank after sleep/lock

#2 Post by Meow »

Does this problem also happen if you do not use the xfce menu to sleep/hibernate, but instead open a terminal window, log in as root using su, and then issue a systemctl hibernate command?

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debiman
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Re: Screen is totally blank after sleep/lock

#3 Post by debiman »

micon wrote:I have a new computer running Debian 9 and xfce4 using lightdm.
i have no personal experience with this, but i know that lightdm usually wants lightlocker (or light-locker or similar).
is that installed?
also iirc lightdm's config file should have an option to specify which locker is used.

have you tried simply blindly entering your password at the blank screen?

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acewiza
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Re: Screen is totally blank after sleep/lock

#4 Post by acewiza »

Are you giving it enough time? I noticed resuming from suspend started taking much longer around a year ago. No idea why, and don't really care.
Nobody would ever ask questions If everyone possessed encyclopedic knowledge of the man pages.

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Re: Screen is totally blank after sleep/lock

#5 Post by Meow »

acewiza wrote:Are you giving it enough time? I noticed resuming from suspend started taking much longer around a year ago. No idea why, and don't really care.
There are different suspend/resume methods, either by swapping out every thread (slow) or swapping out the memory being used in a large chunk (very fast).
And these are also differently reliable, which was the reason to ask whether systemctl hibernate works or not.

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acewiza
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Re: Screen is totally blank after sleep/lock

#6 Post by acewiza »

Meow wrote:There are different suspend/resume methods...
what is the default method?
Nobody would ever ask questions If everyone possessed encyclopedic knowledge of the man pages.

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Re: Screen is totally blank after sleep/lock

#7 Post by acewiza »

Maybe the default method changed? Or maybe people are just talking shyt like they always do around here. :roll:
Nobody would ever ask questions If everyone possessed encyclopedic knowledge of the man pages.

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Re: Screen is totally blank after sleep/lock

#8 Post by Meow »

I do not know which method systemd kicks off by default, have had a few years break from Linux and I am new to systemd.
Well, after the last update the resume process changed at my computer.

Before it was screen going dark, just blinking cursor in the upper left. It was no complete memory reloading, as changing to different processes/programs then caused a swap-in.
After that update it was reloading and uncompressing the image from the swap, displaying progress every 10%.
So my impression is that for some reason the suspend/resume method was changed.
It is a long time ago since I investigated the different hibernate methods (uswsusp, ...) so I cannot deliver detailed information as I forgot much.

However, maybe I'll have to do and have to find and re-read my old notes., as today resume failed for the first time since I installed Debian a few weeks ago.

Edit: Another thing that I noticed after that update was that Apache now fails to start at boot up, forcing me to fire it up manually. So there seem to have been some config changes with that update...

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acewiza
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Re: Screen is totally blank after sleep/lock

#9 Post by acewiza »

We'll see what the OP has to say if they ever respond...
Nobody would ever ask questions If everyone possessed encyclopedic knowledge of the man pages.

micon
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Re: Screen is totally blank after sleep/lock

#10 Post by micon »

I've tried entering my password at the login screen, but no dice.
I don't think timing is an issue - I've waited long past a reasonable amount of time for it to respond.
light-locker is installed.
I'll try the `systemctl hibernate` method when I'm back at the machine tomorrow morning.
Thanks for the input!

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Re: Screen is totally blank after sleep/lock

#11 Post by Head_on_a_Stick »

micon wrote:nvidia drivers: NVIDIA-SMI 375.82 Driver Version: 375.82
Try nouveau instead, the blobs offer more performance but they integrate poorly.
deadbang

micon
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Re: Screen is totally blank after sleep/lock

#12 Post by micon »

I don't think nouveau is an option as the machine is purpose-built for CUDA programming.

Suspending and hibernating (including the `systemctl hibernate` command) work as expected, as long as the lock settings are disabled.

Enabling screen locking when the system suspends, or manually locking the system from the session menu or using the `xflock4` command causes the blank screen behavior. Once the screen is blank and not recoverable, `systemctl restart lightdm` will bring back the login screen, but the session is terminated of course.

light-locker version is 1.7.0-3.

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Re: Screen is totally blank after sleep/lock

#13 Post by Meow »

I do not like login managers because they create all sorts of problems, like what you experience.
I just log in the normal way and then startx.

Maybe you want something like slock or sflock instead, which, unlike many lockers also can block the vts.

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Re: Screen is totally blank after sleep/lock

#14 Post by Head_on_a_Stick »

micon wrote:the machine is purpose-built for CUDA programming
Then why are you using a distribution that has no official support for non-free video drivers? :shock:

Can you please confirm that nouveau fixes this for the benefit of those who run Debian as the developers intend?
deadbang

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debiman
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Re: Screen is totally blank after sleep/lock

#15 Post by debiman »

micon wrote:I don't think nouveau is an option as the machine is purpose-built for CUDA programming.
always this sort of crucial information is provided only after numerous posts, and as an aside, when it should really be in post #1.

anyhow, it should be possible to fix or at least work around the issue.
locate the aforementioned lightdm configuration file, and try to use a different, more primitive locker, maybe it's possible to drop in 'slock'?
if that doesn't work, i'd consider changing display managers. maybe nodm, maybe making do without one completely.

micon
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Re: Screen is totally blank after sleep/lock

#16 Post by micon »

debiman wrote:always this sort of crucial information is provided only after numerous posts, and as an aside, when it should really be in post #1.
I mentioned I was using the nvidia driver, but didn't mention why. I'm pretty new to these sorts of issues, which is why I'm here. This is how the process of discovery works.

I can confirm that after switching to the nouveau driver the issue disappears. I'm running Debian because there are other, external factors that require it.

Thanks for your help in determining that the nvidia driver is the issue. I'll take my questions over to the nvidia forums.

Be well!

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