linux-kernel - Re: [PATCH] Added backlight driver for Acer Aspire 4736

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Date:	Tue, 13 Mar 2012 21:24:54 -0400
From:	Pradeep Subrahmanion <subrahmanion.pradeep@...il.com>
To:	Matthew Garrett <mjg@...hat.com>
Cc:	rpurdie@...ys.net, FlorianSchandinat@....de,
	akpm@...ux-foundation.org, linux-fbdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Added backlight driver for Acer Aspire 4736

On Tue, 2012-03-13 at 13:34 +0000, Matthew Garrett wrote:
> On Tue, Mar 13, 2012 at 06:56:16PM +0530, Pradeep Subrahmanion wrote:
> > I tried giving acpi_backlight = vendor . In that case hot key for
> > brightness control is working. But i think  , it is not calculating the
> > correct value for brightness because increasing brightness after maximum
> > level gives blank screen .
> 
> Which backlight device appears then?
> 

'intel_backlight' appears when i gave option acpi_backlight = vendor. Writing to /sys/class/backlight/intel_backlight/brightness

does not cause any change in brightness.

> > By ' ACPI interface' , I mean 'acpi_video0' inside the
> > /sys/class/backlight. I havn't tried the /sys/class/backlight interface
> > directly . I will try that also.
> 
> So writing values into /sys/class/backlight/acpi_video0/brightness does 
> nothing?


No change in value when writing
to /sys/class/backlight/acpi_video0/brightness.

Another thing is that when i did boot with acpi_backlight = 'acer_wmi' ,
in new kernel (3.3.0-rc7) , it shows following messages , 

[    8.350825] wmi: Mapper loaded
[   10.363975] acer_wmi: Acer Laptop ACPI-WMI Extras
[   10.396186] acer_wmi: Function bitmap for Communication Device: 0x91
[   10.396385] acer_wmi: Brightness must be controlled by generic video
driver

Also there was no interface inside /sys/class/backlight for acer_wmi. 

I also tried writing directly to Embedded controller register .But no
change.

----

Thanks , 

Pradeep Subrahmanion
  


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