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

- From: joeyli \<jlee@suse.com\>
- Date: 2012-03-22 03:27:21 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2012/03/3839551
- Thread: https://ratatoskr.run/linux-fbdev/2012/03/3835160/t.md

```text
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?


thanks
Joey Lee

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