Ubuntu
linux package

  1. Bug #357673
  2. Comment #56

Comment 56 for bug 357673

Revision history for this message
Aaron Roydhouse (aaron-roydhouse) wrote : Re: No notification when sliding audio volume, muting volume, sliding LCD brightness on X31, X32, T60, R50e, T42, R52

Even on new laptops (I'm using an X301) there is no /proc/acpi/ibm/brightness

The brightness is outside of the ibm-specific ACPI stuff and under each monitor, e.g. /proc/acpi/video/VID/LCD0/brightness

There is a folder in 'VID' for each possible monitor output, including the built in LCD. Normally only the built-in LCD has adjustable brightness, but you could imagine that more that one monitor may have adjustable brightness in the future.

cat /proc/acpi/video/VID/LCD0/brightness
levels: 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 100
current: 75

cat /proc/acpi/video/VID/CRT0/brightness
<not supported>

The '/proc/acpi/video/VID/LCD0/brightness' value changes when using the brightness hot keys. It actually jumps two values until it runs out of values and then it change to the last value, e.g. moving up and down you can get to all 16 values but in a two-sweep sequence.

  100 -> 85 -> 75- > 65 -> 55 -> 45 -> 35 -> 25 -> 20 -> 30 -> 40 -> 50 -> 60 -> 70 -> 80 -> 90 -> 100