ubuntu-x-swat team mailing list archive

[Tom Gelinas <tom.gelinas@xxxxxxxxx>]

I have no idea how to effectively monitor changes in /sysfs. The best
method i'm using is to use "tree" to map out Sysfs, and then search for
interesting things and monitor them. If someone could please share a
better method i'd be very appreciative.

I have not found if there is a difference in sysfs between
The hardware brightness buttons on this laptop always affect  /sys/devices/virtual/backlight/acpi_video0/brightness. If change the brightness while running X,  /sys/devices/virtual/backlight/acpi_video0/brightness  is changed but the actual backlight is not affected. If I then switch to a text mode VT and press the backlight up button,  /sys/devices/virtual/backlight/acpi_video0/brightness is increased by 1 and the backlight is set to that level. This level will persist when I switch back to X. 

Nouveau makes a symlink called nv_backlight at /sys/class/backlight,
which links to
sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/nv_backlight,
so I suppose that it is not possible to use nouveau's backlight controls
with the nvidia driver.


/sys/module/video/parameters/brightness_switch_enabled is always set Y when using either nouveau or nvidia. 


It seems that the only solutions for backlight control on this laptop are either to force the nvidia driver to control the backlight, or use the text mode VT's method in X. LED backlights don't have inverters, so I'd think that they shouldnt be producing a buzzing/humming noise. I think it's a very bad idea to force the nvidia driver to control this backlight by default because it may result in physical hardware damage.

-- 
Backlight controls on ThinkPad T510 no longer function when using proprietary drivers
https://bugs.launchpad.net/bugs/562005
You received this bug notification because you are a member of Ubuntu-X,
which is subscribed to nvidia-graphics-drivers in ubuntu.