kern/145306: [acpi]: Can't change brightness on HP ProBook 4510s

Dan Lukes dan at
Fri Jun 11 00:48:13 UTC 2010

David DEMELIER wrote:
>>>>> I got a big output in dmesg but still no message when pressing fn-keys.

>> Then no good news. I can't help you. Your BIOS doesn't create the
>> notification required by ACPI specification section B.7

> Just one information I noticed today : when booting without ACPI
> enabled (it does not boot it stops at a certain point (can't
> remember)) I can change the brightness

With no ACPI the brightness may remain driven by BIOS. With ACPI the 
responsibility may be switched to OS, but the interface doesn't follow 
ACPI specification section B.7.

I assume there is a proprietary interface to do it. Or proprietary 
initialization that turn on standard interface, at least.

> maybe there is a problem between freebsd ACPI <-> the laptop screen


You got some notifications but not those related to brightness keys. I 
doesn't assume there is problem with receiving one type of ACPI 
notification while other can be received with no problem ...


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