[Bugme-new] [Bug 41112] New: HP EliteBook 8460p - Screen brightness not working

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=41112

           Summary: HP EliteBook 8460p - Screen brightness not working
           Product: ACPI
           Version: 2.5
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Power-Video
        AssignedTo: acpi_power-video at kernel-bugs.osdl.org
        ReportedBy: pali.rohar at gmail.com
        Regression: No


Setting brightness level on HP EliteBook 8460p is not working. I tried these
commans:

# cat /sys/class/backlight/acpi_video0/max_brightness 
20
# cat /sys/class/backlight/acpi_video0/brightness 
20
# echo 0 > /sys/class/backlight/acpi_video0/brightness 
# cat /sys/class/backlight/acpi_video0/brightness 
0
# echo 20 > /sys/class/backlight/acpi_video0/brightness 
# cat /sys/class/backlight/acpi_video0/brightness 
20

It did not show me any error, but screen brightness was not changed. And
setting brightness with Fn keys does not working (xev see scancodes, but
nothing happened).

When I disabled ACPI (with acpi=off in grub) brightness keys started working,
but xev does not see scancodes. And all other Fn keys does not working (when
acpi is disabled).

And it is possible to change brightness (with Fn keys) in Grub. But when linux
kernel is loaded (with enabled acpi) brightness keys stop working.

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