GNOME Bugzilla – Bug 660755
brigthness settings on samsung nc10 (driver intel)
Last modified: 2012-02-12 09:05:01 UTC
Hi, Since I’ve upgraded to gnome3.2 (archlinux), The brightness of the screen goes crazy. Here are symptoms : USING KEYBOARD KEYS 1. using fn+brightness down key : dim the brigthness to minimum (no steps) 2. using fn+brightness up key one time : up the brigthness a little (one step) 3. using fn+brightness up key more than one time : up the brightness to max (no steps) USING SCREEN SETTINGS I drag the cursor from left to right, the result is a bit random (sometimes goes to min, sometimes to max, sometimes as I want). IN BOTH CASES sometimes the screen goes stroboscopic, and readjusting the brightness calm it down. hardware : netbook samsung nc10 with intel graphics drivers xf86-video-intel distro : archlinux have a nice day.
Experiencing the exact same thing on a NC10 after update to Gnome 3.2. This can also be seen when screen is activated from idle (dimmed) state. Worked correctly on Gnome 3.0. Hardware: Samsung NC10 using xf86-video-intel Distro: Arch Linux Gnome: 3.2
also reported at https://bugs.archlinux.org/task/26222
Just did some research. Turns out there are two modules in /sys/class/backlight: acpi_video0 and samsung When I change the backlight using the samsung model the the behavior from the original bugreport occurs. But if I use the acpi_video0 module the behavior is more or less as intended (though the light intensity between steps is different). Conclusions * Two modules are loaded as backlight, should it be that way? * The samsung module (from samsung_laptop) seems to be broken for controlling backlight on NC10 ATM. Rodrigue: can you reproduce this? The following commands were used: echo <level> > /sys/class/backlight/samsung/brightness OR echo <level> > /sys/class/backlight/acpi_video0/brightness level goes from 0->max_brightness
Addition to my comment: Using Gnome 3.2.1 (Arch Linux)
Hi, thanks for your researches Erik, but I’m afraid that since I’ve switched to debian stable (gnome2, it works fine btw ^^) I can’t test… But, I can tell devs that the same problem occurs on ubuntu 11.10 (oneiric) with unity (same netbook). So sorry, but I’m too dependent of backlight control.
Rodrigue: Could you please post your kernel version? Since this is probably where the fault is...
same here. uname -a Linux nc10 3.0.0-12-generic #21~ppa3~loms~oneiric-Ubuntu SMP Thu Oct 13 10:07:48 UTC 2011 i686 i686 i386 GNU/Linux also changing via samsung most of the time displays the overlay while changing via apci_video0 does not. additionaly i have a /sys/class/backlight/intel_backlight/. setting the brightness there to anything but 1 make the screen go black (honestly i just tried 2,3 and 4 cause going back to 1 blind is annoying)
One more thing. > cat /sys/class/backlight/acpi_video0/type firmware > cat /sys/class/backlight/samsung/type platform according to http://www.mjmwired.net/kernel/Documentation/ABI/stable/sysfs-class-backlight "firmware" should be preferred over "platform" - correct in my case.
problem fixed with linux kernel 3.2 (gnome 3.2, debian testing) sorry to bother the wrong place…