[alsa-devel] [RFC][PATCH] ASoC: Move symmetric rate check for substreams to hw_params

[Mark Brown]

On Mon, Mar 07, 2011 at 06:21:32PM +0530, Bedia, Vaibhav wrote:
> On Monday, March 07, 2011 5:39 PM, Mark Brown wrote:

> > This means that applications won't be constrained by the
> > current settings so can't automatically choose the required
> > rate.  ALSA is just fundamentally racy here, if you want to
> > reliably open bidirectional streams you need to serialise the
> > startup of the two directions.    

> When a custom application is written then the race condition can be avoided. 

> However right now a simple test like "arecord -f dat | aplay -f dat" fails. One way to make it work
> is to make sure that a call to arecord/aplay (or some dummy app which just sets some valid rate and returns) 
> has been made before both are invoked simultaneously.

For command line testing you can do something like:

  arecord -f dat | (sleep 1; aplay -f dat -) 

to insert a delay if required.  Obviously not all systems will hit the
race.