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 <[email protected]> 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
