[alsa-devel] snd_pcm_pause kills plaback handle on OMAP4

Péter Ujfalusi peter.ujfalusi at ti.com
Tue Sep 27 08:37:31 CEST 2011


Can you try this patch, if it helps:


On Friday 16 September 2011 06:31:09 john at johnandjuliet.com wrote:
> Thanks for the response.
> Yea I guess my question is a bit thin and the setup is a bit more
> complex so I should list the particulars:
> * This is on an OMAP4 BLAZE ES2.2 or 2.3 processor
> * Running Android Linux 2.6.35 from the TI release version G.1
> * I am actually configuring ALSA to utilize the MODEM audio path
> (which is hw:0,5 that routes McBSP2 audio to/from the 6040's speaker and
> mic.)
> * The McBSP is configured for slave mode network SSI with the audio flow
> on slots 0 and 1
> (the default was I2S)
> * McBSP is configured for 8K sps two channel 32-bit samples (though it
> could be 16 bit samples too)
> I guess the way I wrote the first email that I made it sound like it is
> the McBSP that is not working
> however it could be that while I am sending in audio perhaps the McBSP2
> is working (not sure where I could look at data comming in down in the
> kernel <help plz> but if the McBSP2 is working then it could be that the
> data is not getting to the 6040?!
> > On Wednesday 14 September 2011 11:13:22 john at johnandjuliet.com wrote:
> > > I'm trying to control the McBSP2 that is used for the modem in an
> > > android environment (BLAZE OMAP4)
> > 
> > What kernel are you using?
> 2.6.35 released by TI for Android Gingerbread.  TI tags this as their G1
> release (they are up to G3 now)
> > > What I am trying to do is control the audio paths for capture and
> > > playback seperatly like in a SIMPLEX (half duplex) instead of full
> > > DUPLEX mode audio ..
> > 
> > So either playback, or capture, but never both at the same time?
> Yes.  The device cannot do full duplex.  The ALSA config for hw:0,5 is
> to route audio from McBSP2 to/from the 6040 (ABE)
> The stock Android alsa lib package opens up handles for both capture and
> playback and then turns on audio hardware both MICs and Speakers.
> > > I also want to stop the audio without total
> > > shutdown of the audio system.
> > > 
> > > From what I can see that would be to call snd_pcm_pause(handle,bool)
> > > 
> > > But here is what happens.  With the handle forthe plaback path
> > > everything works OK... But if I call that then the capture path
> > > stops
> > > working... even if I try to turn on (unpause) both paths.
> > 
> > So you have both playback and capture opened, if you pause the playback,
> > and release it, then the capture path stops working?
> > Or you mean that doing the pause/release with playback, then closing it,
> > after that the capture is not working?
> If they are both flowing and I pause capture then playback stops and
> though I can un-pause capture playback never comes back.
> I'll have to double check but I think if I pause playback and then
> un-pause it... that too breaks and playback never resumes.
> > > This implies some sort of bug in the omap soc driver?
> > 
> > Everything is possible. I have not heard such about such a problem
> > myself. If this issue exist on OMAP4, it should be present on OMAP3 as
> > well...
> OK.  perhaps though as I just noted I left out that this could actually
> be a problem on the speaker flow out and not the McBSP2 flow in.. What
> do you think?  The OMAP4 audio system is much different than OMAP3 on
> the speaker/mic side so I guess it could be a problem there?
> > Could you be more specific on the scenario?
> > What codec you have attached to McBSP2 port?
> > Are you using ABE, or are you using the McBSP2 port directly?
> I have my own simplex modem connected and it is generating 8ksps audio
> on slot 0 (first 32 bits) and the McBSP is configured that way.
> I am using the ABE to turn on the speaker hardware and the 6040 side of
> things.
> Mostly I am using the TI ALSA layer they provide for Android ALSA audio
> control and simply placed into it at a key point a snd_pcm_pause() for
> when I want to turn the capture off or on and another place for the
> playback to be off or on.
> Typically capture and playback are not both on at the same time.. You
> are either speaking or you are listening.  This is like a CB radio or a
> Walkie Talkie type of situation.  To save power and also reduce static
> the speaker is only turned on when the modem on McBSP2 indicates that it
> wants to play audio and that is when I would do a
> snd_pcm_pause(playbackhandle,0); when the audio from the modem stops and
> I get the signal from the modem then I call
> snd_pcm_pause(playbackhandle,1);
> When I want to talk then I do the snd_pcm_pause(capture_handle,0); and
> when I stop talking then I do the pause on the capture_handle.
> I will have to check but I think if I pause EITHER one then playback
> stops working.  Playback does work if all I do is an open and not mess
> with it and just do the ALSA set controls to turn on the speaker.
> > CC-ing Jarkko to catch his attention...
> > 
> > --
> > Péter

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