Mailinglist Archive: opensuse (1352 mails)

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Re: [opensuse] Black display on media server
On 2018-06-19 11:42, ken wrote:
On 06/17/2018 07:04 PM, Carlos E. R. wrote:


On Sunday, 2018-06-03 at 15:55 +0200, Carlos E. R. wrote:

Hi,

I have an sporadic problem with my media server, currently running Leap
42.3. Typically it is running kodi full screen (on XFCE desktop). I
leave
it running on the night (it is also server for other things full time),
so I just power off the display.

Well, sometimes when I power back on the display it remains "dark grey",
ie, black with backlight on; there is some signal, but it is black. No
response to keyboard at all, that I can see. Most times I can not switch
to console text mode. I can do ssh from another machine, tasks are
running. I kill kodi if it still there, kill the screen saver, "chvt 1",
"init 3"... nothing works, the display does not respond. I have no
resource but reboot the server.

On monitors I've had this sort of issue with, there has been a red/green
LED generally close to the power button.  When this LED is green, it
means the computer still has a connection to the monitor.  When the LED
is red, it means that there is no connection between the monitor and the
computer.  Does your monitor have such an LED?  If so, what does it "say"?

Nope, no such thing.

There is a window that pops up saying "no signal" when moving the cable
to another socket. But no such window before doing the cable move, so
there was some sort of signal then.


I will try enabling power management of the display in XFCE, setting
"switch off" to "never".

Carlos, I'd think you'd want power management to be on; yes, that would
allow the monitor to go black after a specified amount of time, but it
would also allow the monitor to come back on when the computer receives
input from the mouse or keyboard.  IIRC the "specified amount of time"
can be set to forever.

But it doesn't come back, that is the problem. Normally yes, but not on
a few occasions, which sometimes forced me to reboot.


I normally power off the monitor when not using it, on the mains power
strip.



Two other things:

Try hitting Ctrl+Alt+Keypad-Plus and Ctrl+Alt+Keypad-Minus to get the
monitor back from black.  I'm trying to remember from having your same
problems decades ago, but I did find a way to bring an unresponsive
monitor back to life and those two commands force a reread of the
monitor's capabilities, reconnecting to the monitor in the process. 
Those two key commands are explained in the Xorg manpage, if you want
more info on them.

Yes, those keys are for changing the display resolution, I know them. I
have tried them, but not on this machine, sometimes with disastrous
results because whatever machine is unable to cycle back to the original
resolution.



To make it easier to find out what, if anything, crashed, I'd run "ps
-ef --forest > ps.before" when my system is running properly, then the
same command but with output redirected to a different file after the
system horked.  Afterwards I could compare the two files to see what
possibly crashed.  I'd also note if a PID changed; sometimes a server 
(e.g., X) will crash, but then nicely restart without a trace, except it
has a new PID.  Xorg and the stuff around it will be the most relevant.

Hope something here helps.

I can try that, but I know already that it happens when kodi crashes and
it had the display.

--
Cheers / Saludos,

Carlos E. R.
(from 42.3 x86_64 "Malachite" at Telcontar)

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