Arch Linux

I reproduce this error too.

The intel_backlight directory is missing and I am unable to set the backlight brightness of my display. The /sys/class/backlight directory contains only the acpi_video0 directory. Setting a value to the brightness file doesn't affect the brightness of the display.

I have reproduced this problem with 4.11.2-1-ARCH kernel.
Additional informations:
lspci -v: https://pastebin.com/RWymtnZ2
lsmod: https://pastebin.com/fQWvrkdB
dmesg: https://pastebin.com/msnaa73a

With linux-lts (4.9.30-1-lts) the /sys/class/backlight directory contains the intel_backlight (and not acpi_video0) and I can set the brightness value without any problems.

I also have the same problem with both 4.11.2-1 and 4.11.3-1 kernels.
My computer is also an Asus UX305UA.
Best

have you tried editing both the 20-intel.conf and grub file? if that option was working before go to /usr/share/X11/xorg.conf.d and edit the 20-intel.conf file and add the option "Backlight" "acpi_video0" reboot if that doesn't find the backlight controls then we can try adding it to the grub file located at /etc/default/grub then we add GRUB_CMDLINE_LINUX="acpi_video0" then we update it with sudo update grub. with my experience with the intel HD4000 type these two locations will have a greater effect at locating your backlight. You could also try in grub... acpi_backlight=video or acpi_osi=

Hello Damien, thanks for your suggestion. In my case there is no 20-intel file in the folder you mention (ls: 10-evdev.conf 10-quirks.conf 40-libinput.conf 70-synaptics.conf).
The grub file edit "GRUB_CMDLINE_LINUX="acpi_video0"" did not work.
Best,
Jorge

is it an intel backlight? to check type the following in terminal ( ls /sys/class/backlight/ ) if it is we can make a very basic 20-intel.conf file to see if the option will work.

create a file and rename it 20-intel.conf
Then paste the following..

Section "Device"
Identifier "card0"
Driver "intel"
Option "Backlight" "acpi_video0"
BusID "PCI:0:2:0"
EndSection

boot up and if that doesn't work replace "acpi_video0" with "intel_backlight" and see if that works.

Hi Damien

I tried it doesn't work.

On 4.10, I've got the intel_backlight on /sys/class/backlight. On 4.11 it's replaced by acpi_video0.

I ran into the same problem, before facing https://bugs.archlinux.org/task/54471. Enabling CSM in BIOS resolves both issues for me.

Edit: in my cmdline, I have:
acpi_backlight=none acpi_osi=

Works for Asus Zenbook UX305U.

Yesterday I updated to linux 4.11.5-1 and in the following reboots I got a blank screen. Now I enabled CSM as suggested Marcus and got my linux back!

The folder intel_backlight is back and the increase/decrease buttons are working as well as editing the file brigthness in the intel_backlight folder. Moreover, my grub now has a lower and more appropriate resolution (it was too high before this fix).

Thanks for the update and Marcus for the CSM comment.

Just to verify I didi "echo $acpi_backlight" and got an black line, so if I understand ok I have a different setting from Marcus.

Best,
Jorge

Hi,

OK it's working with CSM enabled on bios.
But is it really the good solution?
CSM emulated an old bios on UEFI for compatibility.
But it was working on 4.10 without CSM, so why not on 4.11?

What have been removed on 4.11?

Best,

I've just updated from 4.11.5-1 to 4.11.7-1 and tryied again and the same results:
CSM-enabled boots ok (but slower), but with CSM-disabled and fast boot I get the same blank screen.
Best,
Jorge

Hi,

I am not a Archlinux user but a Fedora one since years.

If I come in this discussion this is because I have also an Asus UX305UA and I have a problem with it.

I did have any problem until kernel 4.11.4 but since kernel 4.11.5 and with all kernel until 4.11.10, I get a black screen during boot.
If I connect an external monitor on HDMI port, I get message on external monitor following message:

"[ 1.308240] [drm:drm_calc_timestamping_constants [drm]] *ERROR* crtc 31: Can't calculate constants, dotclock = 0!
You are in emergency mode..."

I found this bugzilla entry about same problem with Fedora and UX305UA: https://bugzilla.redhat.com/show_bug.cgi?id=1463085

So I would like to know if Archlinux with kernel 4.11.5 and above works fine on Asus UX305UA ?

Thanks for your help.

Hi, yesterday I disabled CSM and set Fast Boot again and everything is working fine (including brightness control). In my case it seems to have been solved through some of the kernel updates (currently I have the 4.15.3-2).
Best.