Ubuntu
linux package

  1. Bug #935778
  2. Comment #5

Comment 5 for bug 935778

Revision history for this message
Seth Forshee (sforshee) wrote : Re: Toshiba R840 - brightness controls work on first boot, but do nothing after suspend/resume

It's hard to tell much from your ACPI tables, essentially they just seem to be handing everything off to the embedded controller. We'll have to experiment a little.

If you look in /sys/class/backlight you'll have a directory for each of the backlight interfaces available on your system. You should see at minimum one named acpi_video0, and probably another one named toshiba. In each directory there will be files named brightness and max_brightness, among others. The allowed range of brightness values are 0 to max_brightness, and you can change the brightness by writing one of these values to the brightness file (as root).

Can you tell me what interfaces you see in /sys/class/backlight, and try writing values to the brightness file to see which of them work after a fresh boot (i.e. without any suspend/resume)? Then do a suspend resume and test them again. Let me know which of them work before the suspend and whether or not any of them work after the suspend. Thanks!