# Re: \[PATCH\] Added backlight driver for Acer Aspire 4736

- From: joeyli \<jlee@suse.com\>
- Date: 2012-03-22 09:36:42 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2012/03/3839644
- Thread: https://ratatoskr.run/linux-fbdev/2012/03/3835160/t.md

```text
於 四，2012-03-22 於 11:26 +0530，Pradeep Subrahmanion �到：
> >From acer acpi ,I came to know that the 4730 series uses new wmi interface .
> 
> http://code.google.com/p/aceracpi/wiki/SupportedHardware
> 

I am not sure what is the WMIDv2, but it's not the current WMI v2 in
acer-wmi driver.

> Thanks ,
> 
> Pradeep Subrahmanion
> 
> On Thu, Mar 22, 2012 at 9:24 AM, joeyli [ref] wrote:
> > 於 四，2012-03-22 於 09:02 +0530，Pradeep Subrahmanion �到：
> >> On Thu, 2012-03-22 at 11:25 +0800, joeyli wrote:
> >> > 於 四，2012-03-22 於 08:03 +0530，Pradeep Subrahmanion �到：
> >> > > On Thu, 2012-03-22 at 09:33 +0800, joeyli wrote:
> >> > > > 於 四，2012-03-22 於 00:39 +0530，Pradeep Subrahmanion �到：
> >> > > > > > This new patch should remove acpi_video0 interface on your machine.
> >> > > > > > Please kindly provide your dmidecode:
> >> > > > > >  dmidecode > dmidecode.log
> >> > > > > >
> >> > > > > > And,
> >> > > > > > please make should the patch really applied, you can do a bit change on
> >> > > > > > pr_info message by yourself.
> >> > > > >
> >> > > > >    Sorry . I think there was some mistake . I tried the patch again. Now
> >> > > > > I see only intel_backlight inside /sys/class/backlight. There is no
> >> > > > > acer-wmi interface . Is this the expected behavior ? . Or am I missing
> >> > > > > anything ?
> >> > > > >
> >> > > >
> >> > > > Yes, this is the expected behavior! But, now I doubt your issue was
> >> > > > workaround by acpi_osi=Linux but not intel_backlight.
> >> > > >
> >> > >
> >> > > > >
> >> > > > >
> >> > > > > >
> >> > > > > > > echo 5 > /sys/class/backlight/acpi_video0/brightness
> >> > > > > > > echo 5 > /sys/class/backlight/intel_backlight/brightness
> >> > > > > > >
> >> > > > > > > But it doesn't make any change .
> >> > > > > > >
> >> > > > > > > In my case  , 'acpi_backlight = vendor' does not make any difference since the hot key control
> >> > > > > > >
> >> > > > > > > already starts working with 'acpi_osi=Linux' option.
> >> > > > > > >
> >> > > > > > > cat /proc/cmdline gives ,
> >> > > > > > >
> >> > > > > > > BOOT_IMAGE=/boot/vmlinuz-3.3.0+
> >> > > > > > > root=UUIDğ197a59-c067-4fd8-ad90-c4d721816077 ro acpi_osi=Linux
> >> > > > > > >
> >> > > > > > >
> >> > > > > > > Thanks ,
> >> > > > > > >
> >> > > > > > > Pradeep Subrahmanion
> >> > > > > > >
> >> > > > > >
> >> > > > > > OK, that's more clearly, please remove acpi_osi=Linux then re-test, I
> >> > > > > > think the hotkey of backlight control only works with acpi_osi=Linux ?
> >> > > > > >
> >> > > >
> >> > > > Does your backlight control still work if you remove acpi_osi=Linux ?
> >> > >
> >> > >    If I remove acpi_osi=Linux , the hot key control stops working .
> >> > >
> >> >
> >> > What is the preload OS in your machine when you bought it? Windows XP,
> >> > Vista or Windows 7?
> >>
> >>    It was Windows XP.
> >>
> >
> > The WDDM driver didn't support by Windows XP, the brightness control on
> > XP should works with _BCM or OpRegion.
> >
> > Wonder how does brightness control work on XP with your machine.
> >
> > I will dig more in your dsdt...
> >
> >

Please kindly try acpi_osi="!Windows 2006", I think it also works to
you.


Thanks
Joey Lee

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