Ubuntu
linux package

  1. Bug #1098216
  2. Comment #41

Comment 41 for bug 1098216

Revision history for this message
Nathaniel Roach (nroach44) wrote : Re: Regression in brightness control on Lenovo Thinkpad X230 and X1 Carbon

Using the -r1-noblpatch kernel (the clean one), I get a shortened "range" i.e. I can use ~30%-70% but accessing values outside that range causes flickering (using gnome3 and the Fn+F7/F8 keys). This seems to be dependent on the value of /sys/class/backlight/acpi_video0/brightness

I manually incremented /sys/class/backlight/acpi_video0/brightness in sets of ten (initially one by one) and no new messages appeared in dmesg, apart from one more of the thinkpad_acpi ones that is also at the base of the previous upload. The brightness changed fine using this method.

"cat /sys/class/backlight/acpi_video0/max_brightness" returns 100.

Using previous kernels (anything >=3.7) I would get exactly the behaviour described in the bug report (unable to shift below ~90%).