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20898
Latitude e7440 A14 bios update breaks brightness key control in Ubuntu
Hello.
e7440 A14, Ubuntu 14.10, kernel 3.18.
It is possible to control brightness writing to /sys/class/backlight/intel_backlight/brightness or via system/brihtness and look, but buttons do not work.
According to xev Fn/Up or Down simply do not generate any event.
To restore functioning I need to run suspend to RAM (not hibernate). I failed to detect anything specific in pm-utils scripts and it seems that suspend helps by itself.
Unfortunately I do not have Windows to check, but I definitely did not have this issue against neither A08 nor A12.
ilejn
3 Posts
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February 15th, 2015 07:00
Adding boot parameters acpi_osi=Linux acpi_backlight=vendorresolves this issue for me.
ilejn
3 Posts
0
February 15th, 2015 06:00
acpi_listen says only
PNP0C14:00 000000d0 00000000
both for brightness Up and Down, while after resuming from suspend it is
video/brightnessdown BRTDN 00000087 00000000
PNP0C14:00 000000d0 00000000
video/brightnessup BRTUP 00000086 00000000
PNP0C14:00 000000d0 00000000