Re: [PATCH 3/5] thinkpad-acpi: make volume subdriver optional

[Jerone Young <jerone.young-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>]

On Mon, 2009-12-28 at 11:17 -0200, Henrique de Moraes Holschuh wrote:
> On Sun, 27 Dec 2009, Ian Molton wrote:
> > Not directly related to your patch but I thought I'd mention...
> > 
> > I've noticed issues with my X200 re: routing audio before / after docking.
> 
> ThinkPads used to route line-out to the dock, with a fixed 1.1dB amplifier
> (0.1dB increase) in the audio path, and had the volume control for
> headphones and speakers done in a different audio path, extracted before the
> line-out amplifier.  The PeeCee beeper channel was routed to the headphones
> and speakers, only.
> 
> If Lenovo tried to reproduce that with the HDA mixer but without the "Laptop
> Apudio Controller" the IBM thinkpads had, I wouldn't be surprised if it
> causes massive ALSA disruption should the firmware screw with the HDA mixer
> registers behind ALSA's back.  Try asking the kernel to enable OSI(Linux) in
> ACPI...  I always forget the kernel command line parameter to do that, but
> it is documented in the usual place.

"acpi_osi=Linux" is the kernel command line param your looking for.

> 



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