[linux-audio-dev] dmix and jack

[James Courtier-Dutton]

Paul Davis wrote:
> On Mon, 2006-01-30 at 20:05 +0000, James Courtier-Dutton wrote:
>> voidcreature at paradise.net.nz wrote:
>>> Has anyone managed to successfully get jackd talking to dmix?
>>>
>>> My dmix setup works fix (i run VoIP stuff, artsd, and other assorted junk 
>>> through it daily).
>>>
>>> jackd works great when connect to hw:0,0 or to plughw:0,0 (with the warning), 
>>> but if I point it at my dmix'd "default"  it sits there with 100% CPU usage, 
>>> and doesn't otherwise operate.
>>>
>>> Does anyone have this combination of jack and dmix working?
>>>
>> It is due to the fact that the alsa programming in jackd has been 
>> implemented wrongly. The poll revents are not handled correctly.
>> This results is OK operation when using hw:0,0, but likely to fail for 
>> more exotic alsa configurations like dmix.
> 
> i will happily take a patch for this. or is it just the MMAP_COMPLEX
> patch and nothing more?
> 
> --p
> 

Paul,

If I get a moment, I will try to get a patch together for jackd this 
weekend. It is just a matter of adding a few lines of code, so hopefully 
won't take long.

If you want to make a head start, you need to add
snd_pcm_poll_descriptors_revents() calls.

I attach some GPL code from another project that should illustrate the 
method to use.

James
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