Re: Fwd: Brightness on HP EliteBook 8460p

[joeyli <jlee@suse.com>]

於 日，2011-12-18 於 23:47 +0800，joeyli 提到：
> Hi Pali, 
> 
> 於 日，2011-12-18 於 11:59 +0100，Pali Rohár 提到：
> > On Friday 09 December 2011 16:46:29 Pali Rohár wrote:
> > > On Friday 09 December 2011 22:49:09 joeyli wrote:
> > > > Hi Pali,
> > > > 
> > > > 於 五，2011-12-09 於 22:36 +0800，Li Joey 提到：
> > > > 
> > > > > ---------- Forwarded message ----------
> > > > > From: Pali Rohár <pali.rohar@gmail.com>
> > > > > Date: 2011/7/15
> > > > > Subject: Brightness on HP EliteBook 8460p
> > > > > To: linux-acpi@vger.kernel.org
> > > > > 
> > > > > 
> > > > > Hello,
> > > > > 
> > > > > on my HP EliteBook 8460p is not possible to set display brightness
> > > > > when ACPI
> > > > > is enabled in kernel. Entries in sysfs is properly created without
> > > > > errors. But
> > > > > when I try write any value
> > > > > to /sys/class/backlight/acpi_video0/brightness
> > > > > nothing happened (and no error is in dmesg). When I press Fn key for
> > > > > chaining
> > > > > display brightness kernel send correct key event (tested with xev)
> > > > > but
> > > > > nothing
> > > > > happened too.
> > > > > 
> > > > > When I disabled ACPI (acpi=off in kernel command line) all Fn keys
> > > > > are
> > > > > broken
> > > > > and not working (no events in xev). But brightness keys working (I
> > > > > think on HW
> > > > > level, because xev does not see it) - increase and decrease display
> > > > > brightness.
> > > > > 
> > > > > So what can I do with my notebook? I think that there is error/bug
> > > > > in
> > > > > BIOS or
> > > > > ACPI because with disabled ACPI brightness working. But with
> > > > > disabled
> > > > > ACPI is
> > > > > notebook unuseable (no battery info, no Fn keys, no WIFI rfkill,
> > > > > ...).
> > > > > Can
> > > > > somebody help me with this problem?
> > > > > 
> > > > > --
> > > > > Pali Rohár
> > > > > pali.rohar@gmail.com
> > > > 
> > > > You can try to put kernel parameter:
> > > > 	acpi_osi="!Windows 2009"
> > > > 
> > > > to /boot/grub/menu.lst, then reboot look at maybe better.
> > > > 
> > > > And,
> > > > could you please kindly share DSDT and dmidecode to me?
> > > > 
> > > > Plesae login by root then:
> > > > 	% acpidump > acpidump.dat
> > > > 	% dmidecode > dmidecode.log
> > > > 
> > > > Thanks a lot!
> > > > Joey Lee
> > > 
> > > Hello,
> > > 
> > > adding any acpi_osi values did not changed anything (also tried other osi
> > > strings from decompiled DSDT table). Brightness problem is in both BIOS and
> > > UEFI boot mode.
> > > 
> > > I attached acpidump and dmidecode output from bios and uefi mode too.
> > 
> > Did you find way how to control display brightness?
> > 
> > -- 
> > Pali Rohár
> > pali.rohar@gmail.com
> 
> I am really sorry for I am sticking on another tough issue.
> I will look at your DSDT tomorrow.
> 
> 
> Thanks
> Joey Lee
> 

I just look at the DSDT of HP EliteBook, this machine check _OS name
string, it's essentially obsolete.

Please add the following kernel parameter to /boot/grub/menu.lst:
	acpi_os_name="Windows 2009"

Let's by-pass the _OS name check first, hope it fix this issue.


Thanks
Joey Lee