[SOLVED] ASUS Screen Brightness Not Working

Question

I have been trying for a few hours to get my screen brightness to work properly. I'm on an ASUS Zenbook Prime UX31A with kernel 3.9.6-1. I'm using efibootmgr to boot.
According to the wiki page and numerous posts, I need to use the acpi_osi="!Windows 2012" boot parameter. When I set it using efibootmgr, the keyboard backlight keys work (Fn+F[34]), but the screen brightness keys (Fn+F[56]) do not work. I have tried the following in efibootmgr:
# efibootmgr -c -w -d /dev/sda -p 1 -L "Arch Linux" -l '\EFI\arch\vmlinuz-arch.efi' -u initrd=EFI/arch/initramfs-arch.img root=UUID=d0b32080-84f0-4c6b-933b-f62b880afc09 ro rootfstype=ext4 efi_no_storage_paranoia elevator=noop acpi_osi=Linux add_efi_memmap
# efibootmgr -c -w -d /dev/sda -p 1 -L "Arch Linux" -l '\EFI\arch\vmlinuz-arch.efi' -u initrd=EFI/arch/initramfs-arch.img root=UUID=d0b32080-84f0-4c6b-933b-f62b880afc09 ro rootfstype=ext4 efi_no_storage_paranoia elevator=noop acpi_osi=intel add_efi_memmap
# efibootmgr -c -w -d /dev/sda -p 1 -L "Arch Linux" -l '\EFI\arch\vmlinuz-arch.efi' -u initrd=EFI/arch/initramfs-arch.img root=UUID=d0b32080-84f0-4c6b-933b-f62b880afc09 ro rootfstype=ext4 efi_no_storage_paranoia elevator=noop acpi_osi= add_efi_memmap
and a few others. The particularly peculiar thing is when I use a UEFI shell to boot with my script:
echo -on
\EFI\arch\vmlinuz-arch.efi root=UUID=d0b32080-84f0-4c6b-933b-f62b880afc09 ro rootfstype=ext4 add_efi_memmap efi_no_storage_paranoia initrd=EFI/arch/initramfs-arch.img elevator=noop acpi_osi="!Windows 2012"
it works fine (both keyboard backlight and screen brightness).
What am I doing wrong? My hunch is that I'm doing something wrong with the formatting of acpi_osi="!Windows 2012" but I'm pretty sure I've tried every combination of different quotes and escaping different things. It's also worth nothing that the "!" gets interpreted by bash in some of these permutations making efibootmgr not actually run.
Last edited by tobit (2013-06-30 02:37:30)

Answer 1

WonderWoofy wrote:
Because you are entering it in a shell, you need to escape some of the things in the acpi_osi="!Windows 2012" string.  So for example, the double quotes are intended to be entered exactly as is in the resulting efibootmgr entry, so these should be esacped since they would otherwise have a special meaning in the command line.  The same is true for the exclamation point.  So I think you would have to do:
efibootmgr -c -w -d /dev/sda -p 1 -L "Arch Linux" -l '\EFI\arch\vmlinuz-arch.efi' -u "initrd=/EFI/arch/initramfs-arch.img root=UUID=d0b32080-84f0-4c6b-933b-f62b880afc09 ro rootfstype=ext4 efi_no_storage_paranoia elevator=noop acpi_osi=\"\!Windows 2012\" add_efi_memmap"
BTW, this is just a copy/paste of one of the entries above (slightly fixed).  I added a '/' to your initrd entry, as it is supposed to be an absolute path, not a relative one.
Edit: I too started out with a direct efibootmgr entry when getting to know UEFI.  But I think that a better solution is to use a boot manager.  I like gummiboot, but I also keep rEFInd set up as well.  By doing this, if you ever want to chane something on your kernel command line, you can just edit the config before reboot.  But I think that were it is really useful is if you need to modify the kernel command line before you boot, as it is not possible with a direct efibootmgr entry.  If you want to make it seem seamless, just set the timeout to zero in efibootmgr, and then if you want to get to the menu, you just hold the spacebar while booting. 
The reason I wanted to use a direct efibootmgr entry was because I thought it would be faster.  But because gummiboot and systemd will actually give you the time it takes to boot which includes the time in the firmware (POST) as well as the time it takes to get through the boot manager, I have actually found that my system takes a whole 14ms from the end of POST to starting to load the kernel.
Edit2: BTW, I also quoted the entire srting of arguments on the kernel command line, which it need in order to be fed to the '-u' option as a single string.
I'm afraid that still doesn't work. I've tried similar things and tried that specifically.  In case you're wondering, the command you listed gives me the following output:
$ sudo efibootmgr -v
BootCurrent: 0000
Timeout: 2 seconds
BootOrder: 0000
Boot0000* Arch Linux HD(1,800,96000,bee2185e-de97-4dc0-9614-830639991bc3)File(\EFI\arch\vmlinuz-arch.efi)i.n.i.t.r.d.=./.E.F.I./.a.r.c.h./.i.n.i.t.r.a.m.f.s.-.a.r.c.h...i.m.g. .r.o.o.t.=.U.U.I.D.=.d.0.b.3.2.0.8.0.-.8.4.f.0.-.4.c.6.b.-.9.3.3.b.-.f.6.2.b.8.8.0.a.f.c.0.9. .r.o. .r.o.o.t.f.s.t.y.p.e.=.e.x.t.4. .e.f.i._.n.o._.s.t.o.r.a.g.e._.p.a.r.a.n.o.i.a. .e.l.e.v.a.t.o.r.=.n.o.o.p. .a.c.p.i._.o.s.i.=.".\.!.W.i.n.d.o.w.s. .2.0.1.2.". .a.d.d._.e.f.i._.m.e.m.m.a.p...
I also tried putting the -u argument in single quotes so that I don't have to escape the double quotes or the !. That also didn't work. Thanks for your suggestions, I'd be happy to try more, I've tried a lot already to no avail :-(
count0 wrote:On my Asus X201E, the screen brightness keys only work when I add "acpi_osi=" to my kernel parameters, with no arguments. You could try that.
That's the third option I say that I tried in my original post.