The problem is cause by gsd-backlight-helper - it query udev for "backlight" devices, and then pick the first device with type "firmware", "platform", or "raw".
When running on this mahcine (Asus X101CH), it find these devices: 1. firmware: /sys/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0 2. platform: /sys/devices/virtual/backlight/psb-bl 3. raw: (null) Then it uses "/sys/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0", becuase firmware is prefered. This device does effect the display brightness, unless the system is booted with acpi_osi=Linux acpi_backlight=vendor(see above). This patch change the prefered device to be "platform", using "/sys/devices/virtual/backlight/psb-bl", which fix the brightness slider in system setting application. ** Patch added: "Experimental fix for system setting brightness panel on Asus X101CH" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1140581/+attachment/3554519/+files/gsd-backlight-helper.patch ** Tags added: patch -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1140581 Title: Brightness system settings do not work on Asus Eee PC X101CH To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1140581/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
