[pulseaudio-discuss] [PATCH v5 0/7] New API for Bluetooth A2DP codecs

[Pali Rohár]

On Friday 25 January 2019 11:04:22 Tanu Kaskinen wrote:
> On Wed, 2019-01-23 at 18:52 +0100, Pali Rohár wrote:
> > On Wednesday 23 January 2019 19:16:16 Luiz Augusto von Dentz wrote:
> > > Hi Pali,
> > > On Sat, Jan 19, 2019 at 7:19 PM Pali Rohár <pali.rohar at gmail.com> wrote:
> > > > I think that this patch series is now ready for review and testing. All
> > > > needed parts are finished.
> > > > 
> > > > The only problem is with asynchronous profile switching as function
> > > > pa_card_set_profile() does not support it. All details are in patch
> > > > "[PATCH v5 5/7] bluetooth: Modular API for A2DP codecs".
> > > > 
> > > > So can you look at this patch series and review it?
> > > 
> > > I tested this today, it seems to work fine with sbc but with
> > > faststream there seems to be some problem somewhere as it does seems
> > > to consume too much cpu time. Regarding set_profile that is something
> > > I think we will need to address otherwise the UI is pretty much
> > > useless to switch as it doesn't seems to react well when -EAGAIN is
> > > returned, we could perhaps block on SetConfiguration since we do block
> > > on Acquire anyway, or you have already tried that?
> > 
> > Yes, I tried it. Pulseaudio blocks communication and therefore it also
> > does not receive following DBus requests from bluez and so
> > SetConfiguration timeout.
> > 
> > In fact -EAGAIN is just dropped in pulseaudio bluetooth module and
> > replaced by -1. I just wanted to "highlight" that part of code, so I
> > used -EAGAIN, but it has same meaning as any other non-zero value.
> > 
> > I was thinking about it and we could block this on another layer.
> > pa_card_set_profile() is called when application request to change
> > profile via PA socket. So extend pa_card_set_profile() API to pass
> > callback function which would be called after profile is changed
> > asynchronously. And just block user request until callback is called.
> > 
> > Maybe some other people who understand pulseaudio better can help? How
> > to implement asynchronous profile switching?
> 
> To me it seems that either pa_card_set_profile() should be made
> asynchronous, which would be nice, because it would allow errors to be
> reported properly, or the bluetooth code should just initiate the
> profile change operation and pretend that the switching always
> succeeds. In the latter option, in case of failure the bluetooth code
> would switch to the off profile.
> 
> I'm fine with either option.

Seems that immediate switch to profile is easier as implementing whole
asynchronous operations.

-- 
Pali Rohár
pali.rohar at gmail.com
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