[Gta04-owner] alsaloop and poll issues with the modem ALSA driver.

Dr. H. Nikolaus Schaller hns at goldelico.com
Sun May 20 19:09:14 CEST 2012

Am 20.05.2012 um 18:24 schrieb Denis 'GNUtoo' Carikli:

> Hi,
> I am trying to get a good forwarder to work on the gta04 A3 for SHR
> (The forwarder is the main blocking thing for me, since I've no gta04 A4).
> Here are the result from debugging alsaloop:
> If the modem is in call, the poll system call behave normally:
> poll took 246094us //from alsaloop
> but if the modem is not in a call:
> the poll will take a lot less:
> poll took 31us //from alsaloop
> which will result in 100% or near 100% CPU usage.
> I think that the right thing is to fix the audio driver or the ASOC framework.

This may have to do with the PCM clock/frame sync that is coming
from the modem. And it starts only at the moment the connection is

Maybe, a poll() before the clock arrives fails and returns some error.
Could be some error that isn't reported to the user space.

Radek & Neil may know a little more about this.

To reduce CPU usage, you could try to find some indication about
being in call/not in call and sleep the forwarder process a little.


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