Ubuntu
linux package

  1. Bug #826386
  2. Comment #19

Comment 19 for bug 826386

Revision history for this message
Julian Wiedmann (jwiedmann) wrote : Re: No backlight display Acer Aspire 5734Z

Okay, let's stick with Oneiric. I assume that when the machine comes up with no backlight, adjusting the brightness (by using Hotkeys or the GUI) doesn't work either?

If that's correct, here's a couple of things you can test:
1. see what's in acpi_video/bl_power
2. when you try to adjust the brightness, do acpi_video/brightness and /actual_brightness change? Are they still in sync?
3. control the backlight acpi_video0 manually (by writing to acpi_video0/brightness) and see if /brightness or /actual_brightness change
4. reboot with 'acpi_backlight=vendor' on the command line (& confirm that acpi_video0 no longer shows up in sys/class/backlight) and go through the same routine with intel_backlight

[the documentation for /sys/class/backlight is at http://kernel.ubuntu.com/git?p=ubuntu/ubuntu-oneiric.git;a=blob_plain;f=Documentation/ABI/stable/sysfs-class-backlight ]

(btw: what's in /sys/class/backlight on your Maverick system? Are you able to change the brightness on that system?)