FWIW Mine is a different Samsung machine (NP900x3d), my Ubuntu version is 12.10. I've tried with/without acpi_backlight=vendor .
More precisely this is my current boot command line: luis@sams9:~$ cat /proc/cmdline BOOT_IMAGE=/boot/vmlinuz-3.5.0-26-generic root=... ro quiet splash i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1 vt.handoff=7 (The i915* options are my own customizations) The output: * with acpi_backlight=vendor added (Fn key combination does not work): [ 5.613] (--) intel(0): found backlight control interface /sys/class/backlight/samsung * without acpi_backlight=vendor, as it is in the referred /proc/cmdline (Fn key combination works): [ 5.097] (--) intel(0): found backlight control interface /sys/class/backlight/acpi_video0 The weird thing is that acpi_backlight=verdor worked when BIOS was in UEFI mode. I've changed this to CSM mode after some research about the infamous firmware bug: http://mjg59.dreamwidth.org/22855.html Unfortunately I cannot provide more info for the UEFI mode. The main advantage of using the samsung interface is that the minimum brightness threshold is lesser than in the native acpi_video interface, the former allows to dim completely the screen with the corresponding gaining in power saving. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1104529 Title: Screen brightness does not work properly on samsung chronos 7 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1104529/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
