Display brightness problem on ThinkPad X1 Carbon 2015 (3rd Gen)

Question

I am using ThinkPad X1 Carbon 2015 (3rd Gen) with 1920x1080 display (no touchscreen), running Ubuntu 14.04 with all patches applied (14.04.2 equivalent, I think).

I used this post: Lenovo X1 Carbon 2015 3rd gen 20 BS - trackpoint, clickpad and wifi

1. Create /etc/modprobe.d/thinkpad_acpi.conf containing only one line options thinkpad_acpi force_load=1

2. Change /etc/default/grub as follows:

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
   

3. sudo update-grub

4. Add echo 167 > /sys/class/backlight/intel_backlight/brightness to /etc/rc.local

5. reboot

This procedure produced the following result:

• Display brightness remains the minimum level (0). I installed indicator-brightness and set to maximum (15) but it doesn't help.
• I changed brightness from display settings and no changes are happening.
• Fn+F5/F6 combinations do not work. On-screen display can be seen, but brightness cannot be changed by these key compbinations (actually, this is a small problem. I could change manually display brightness if everything was working fine).

• In /var/log/dmesg, there is one entry

  [    1.549321] thinkpad_acpi: Standard ACPI backlight interface not available, thinkpad_acpi native brightness control enabled
  

The worst difficulty I am facing is the minimum brightness of display.

Answer 1

Intermediate self-resolution. My ThinkPad X1 Carbon (3rd Gen) now displays maximum (not minimum) brightness.

From the previous procedure, I deleted the entry in /etc/rc.local beginning with echo 167 > .... This made sense.

No other settings were changed.

Brightness control still does not work, but the current situation is far better than being permanently stuck on minimum brightness.

Still, is there any solution to make brightness control in ThinkPad X1 Carbon 2015 (3rd Gen)?