[alsa-devel] How to support software mixing on QUALCOMM 72XX without mmap?

[Mark Brown]

On Sun, May 30, 2010 at 12:54:17AM +0800, Berg wrote:

>     I'm porting ASLA1.0.23 to qualcomm 72xx base on ARM11.

You might want to coordinate your efforts with the other people working
on Qualcomm chipsets.  I've CCed in Brian Swetland who I know is one
such person but there were a few others.

>     The first instance,"aplay test.wav", works now, but the second
> instance should fail with "device busy" error message.
>     I have tried plug dmix and dshare "aply -D plug:mycard
> test.wav", but met a fail again for the soc chip doesn't support mmap.
> Of course,pcm_mycard is defined in /etc/asound.conf.

I'd generally suggest PulseAudio over dmix for software mixing.

>     My questions are:
>         1)Is  software mixing  implemented in ALSA Driver,or in ALSA LIB?

It's implemented in user space, via an ALSA library plugin.