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Date: Wed, 11 May 2011 20:14:42 +0200
From: Mathieu Sonet <contact@elasticsheep.com>
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Subject: Re: [Qemu-devel] [PATCH] Add AACI audio playback support to the ARM
 Versatile/PB platform
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To: Paul Brook <paul@codesourcery.com>
Cc: qemu-devel@nongnu.org

Paul Brook wrote:
>> The PL041 driver provides an interface to an ACLink bus.
>> The LM4549 driver emulates a DAC connected on the ACLink bus.
>> Only audio playback is implemented.
> 
> Shouldn't this be shared with the other AC97 devices?
> 
> Paul

I organized the code in 3 different drivers (PL041 <=> ACLink <=> 
LM4549) to decorrelate the codec interface from its implementation. This 
could allow the use of alternative AC97 models with the same PL041 
implementation.

On the other hand the current ac97.c implementation is a closely coupled 
combination of a PCI/ACLink bridge (Intel 82801AA) with a generic AC97 
codec. This has prevent me to easily reuse this code.

The milkymist-ac97 implementation is another case. It looks like a basic 
implementation with the AC97 registers directly mapped on the system bus.

Using the ACLink bus I defined, it could be interesting to implement 
separately the PCI/ACLink bridge from ac97.c.

Is it what you mean by saying this should be shared with the other AC97 
devices ?

Mathieu