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Re: Issues resuming from hibernation

Hey solitone,

I happen to have '/sys/class/backlight/intel_backlight/' so I played
with that. I have been echoing to it.

I noticed that the values there don't seem to have a direct relation
with the actual brightness. By switching Fn + F7 and F8, different
values are put in those files.

What I mean with that is, I tap the function key three times down and
three times up, the backlight comes back to it's original luminance.
When I echo to that file the value shown at three times down, the
backlight changes, but after this, I can't get it to it's original
setting, with echoing the value that was shown. After this, by using the
function key, down and up, till I can tell it is the same luminance,
then the value shown isn't any longer the same.

Are you sure you need to switch the backlight off I ask. I reckon, the
backlight comes with it's own electronics, but by echoing a real low
value, it isn't actually turned off [according to the kernel I suppose],
and then you can echo to it, to see if you can get your preferred value,
and if this is stable [the backlight luminance stays at what you have
echo'd to it]

I'm not sure if this will be helpful, but it is helpful to see if
echoing '0' to it, gives the same problem.

Also, when you are confident how the kernel/ backlight responds to a low
value and zero value, then, if the system hibernates, you can remove the
battery, wait a moment, put it back in [to make sure your laptop is
really without current], see if that comes back [I suppose it will,
hence it hibernates], then you can be sure you won't have to turn off
the backlight. 

Let me know if I missed something. Also, you might want to give xrandr/
xbacklight a try.

Richard Waterbeek <richardwbb@versatel.nl>
The Netherlands

solitone schreef op di 10-01-2017 om 07:01 [+0100]:
> On Tuesday, January 10, 2017 3:12:11 AM CET Richard Waterbeek wrote:
> > Do you have other strange things going on when the system comes back
> > from hibernation or is it only the wireless connection that is being
> > thrown out I wonder.
> Hi Richard,
> now wireless network works perfectly well after resuming from hibernate. 
> There's another thing though, that I wrote about in another branch of this 
> thread. 
> If the screen is off and then the system hibernates, when it resumes the 
> screen is switched off again, and there's no way to turn it on. When the 
> system starts resuming the screen is on, I can see boot messages, but at the 
> end of the resume process the screen is switched off.
> The system is perfectly up and running, and I can ssh into it. From ssh I've 
> checked that, after resume, I have the following values in the three backlight 
> files brightness, actual_brightness, and bl_power:
> $ cat /sys/class/backlight/intel_backlight/brightness 
> 1388
> $ cat /sys/class/backlight/intel_backlight/actual_brightness 
> 0
> $ cat /sys/class/backlight/intel_backlight/bl_power 
> 4
> bl_power = 4 means the screen is off.
> Trying the following command from ssh has no effect--it doesn't change the 
> value in bl_power, and the screen doesn't turn on:
> $ xset -display :0 dpms force on
> I get the issue everytime I hibernate with bl_power set to 4 (screen off).
> I've sent a bug report, but I don't know whether it's the right place and it 
> will ever be considered:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=850221
> Thanks & Regards,
>   Davide

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