Bug 41112

Summary:	HP EliteBook 8460p - Screen brightness not working
Product:	ACPI	Reporter:	Pali Rohár (pali)
Component:	Power-Video	Assignee:	acpi_power-video
Status:	CLOSED DUPLICATE
Severity:	normal	CC:	rui.zhang
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:		Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	acpidump

Description Pali Rohár 2011-08-14 08:59:43 UTC

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.

Comment 1 Zhang Rui 2012-01-18 05:34:00 UTC

The problem has not been fixed yet, right?

please attach the acpidump output of this laptop.

Comment 2 Pali Rohár 2012-01-18 11:50:58 UTC

Created attachment 72105 [details]
acpidump

Comment 3 Pali Rohár 2012-02-05 12:35:50 UTC

More info is here: http://www.mail-archive.com/platform-driver-x86@vger.kernel.org/msg02862.html
Brightness control maybe need to be implemented in radeon driver...

*** This bug has been marked as a duplicate of bug 40862 ***