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Subject: Re: [PATCH] AC97 support for low power codecs
From: Liam Girdwood <Liam.Girdwood@wolfsonmicro.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, Jeff Garzik <jgarzik@pobox.com>,
       lkml <linux-kernel@vger.kernel.org>
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On Tue, 2005-01-04 at 15:08, Takashi Iwai wrote:
> 
> Does writing RESET on such a codec must be avoided always?
> Or can one power up again by writing some values on POWER register?
> 

Writing RESET causes an AC97 codec to return to it's default state. On
some codecs this is state is "power down" and therefore undesirable
during a call to probe.

The only way to wake such a codec is via an AC97 warm reset.

Liam