Brightness keys and booting the kernel

[Nikolay Tychina]

2012/5/5 matt <sendtomatt at gmail.com>:
> On 05/01/12 10:13, Nikolay Tychina wrote:
>>>
>>>  >  Considering the fact that brightness keys work until kernel is
>>> loaded,
>>>  >  is it possible to make them work
>>>  >  after the kernel is booted in some simple way?
>>>  >  I remember my previous laptop was able to control brightness without
>>>  >  any acpi_* modules and disregarding
>>>  >  OS running.
>>>
>>> What make and model laptop?  What OS?  (this one, and the previous?)
>>>
>>> % head -24 /var/run/dmesg.boot
>>>
>>> should provide a clue or two.
>>>
>>> cheers, Ian
>>
>> This is Samsung RV511-S02 which runs FreeBSD 9-RELEASE, previous was
>> Acer Aspire 5520G running FreeBSD 8-STABLE until it burned away in
>> 2010, and I couldn't find dmesg for it.
>>
>> Regards
>>
>>
>> ACPI set debug layer 'ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS' level
>> 'ACPI_LV_ERROR'
>> Copyright (c) 1992-2012 The FreeBSD Project.
>> Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
>>        The Regents of the University of California. All rights reserved.
>> FreeBSD is a registered trademark of The FreeBSD Foundation.
>> FreeBSD 9.0-RELEASE #1: Thu Feb 23 18:33:29 MSK 2012
>>     nicholas at rv511:/usr/obj/usr/src/sys/GENERIC amd64
>> CPU: Intel(R) Core(TM) i3 CPU       M 380  @ 2.53GHz (2527.05-MHz K8-class
>> CPU)
>>   Origin = "GenuineIntel"  Id = 0x20655  Family = 6  Model = 25  Stepping
>> = 5
>>
>> Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
>>
>> Features2=0x9ae3bd<SSE3,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,POPCNT>
>>   AMD Features=0x28100800<SYSCALL,NX,RDTSCP,LM>
>>   AMD Features2=0x1<LAHF>
>>   TSC: P-state invariant, performance statistics
>> real memory  = 4294967296 (4096 MB)
>> avail memory = 3940532224 (3757 MB)
>> Event timer "LAPIC" quality 600
>> ACPI APIC Table:<PTLTD           APIC>
>> FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
>> FreeBSD/SMP: 1 package(s) x 2 core(s) x 2 SMT threads
>>  cpu0 (BSP): APIC ID:  0
>>  cpu1 (AP): APIC ID:  1
>>  cpu2 (AP): APIC ID:  4
>>  cpu3 (AP): APIC ID:  5
>> _______________________________________________
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>> To unsubscribe, send any mail to "freebsd-acpi-unsubscribe at freebsd.org"
>>
> I know that Thinkpads (obviously not the same but the information may be
> useful) start in "BIOS" mode, where acpi does not handle most hotkeys,
> brightness etc. So the brightness keys work. As soon as acpi attaches,
> however, it "trapdoors" into ACPI mode, where it expects Windows or Linux
> drivers to handle hotkeys and call either acpi video extensions or other
> ACPI methods to initiate display changes and brightness. Have you tried
> using the acpi_video module?
> The reason it works during early kernel and prior on Thinkpads is due to the
> fact it hasn't been "trapdoored" into ACPI mode yet.
>
> Matt

I have tried it, but changing brightness in sysctl doesn't affect anything.
Have just found samsung-laptop.c from linux that reads "This driver is
needed because a number of Samsung laptops do not hook their control
settings through ACPI.  So we have to poke around in the BIOS to do
things like brightness values, and "special" key controls."
heh

Nikolay