[Openvortex-dev] Re: au88x0 modem

[Raymond]

Sasha Khapyorsky wrote:
> On 17:35 Thu 15 Sep     , Sasha Khapyorsky wrote:

> 3. DMA
>
> After some looking in au88x0 driver I think that it is possible that
> modem could use one ADB channels (predefined or programmable) for pcm
> data transfers (just like regular audio), similar scheme may be found
> with some other devices like ali5451.
>
> If so we could try to find channel numbers (should be two - for playback
> and capture). It is very possible that channels should be configured
> somehow first.
>
> Philipp, How looks your 'aplay -l' output?
>
>
> ANYBODY knows something about modem DMA/PCM with au88x0, please advise.


The easy way is to create a PCM device "modem" on au8810


DMA -> FIFO -> SRC -> MIXIN --------> MIXOUT -> MC97(Modem Out)
                        |
                        +-----------> MIXOUT -> EQ -> AC97(Audio Left)

                                Modem Speaker  On or Off

                                  +-> MIXOUT -> EQ -> AC97(Audio Right)
                                  |
DMA <- FIFO <- SRC <- MIXOUT <- MIXIN <-------- MC97(Modem IN)


or


DMA -> FIFO -> SRC -> MC97(modem) (Playback)

DMA <- FIFO <- SRC <- MC97(modem) (Capture)



What is the difference between modem application and audio application ?

Do the modem application open two PCM streams (one for playback and the 
other for capture )?

Where is the class SND_PCM_CLASS_MODEM specificed in the driver ?