[pulseaudio-discuss] [PATCH v4 0/3] use bluetooth HFP in pulseaudio when available

[James Bottomley]

On Wed, 2017-09-20 at 20:41 +0200, Georg Chini wrote:
> On 20.09.2017 20:10, James Bottomley wrote:
> > 
> > On Wed, 2017-09-20 at 18:11 +0200, Georg Chini wrote:
> > > 
> > > On 20.09.2017 01:27, James Bottomley wrote:
> > > > 
> > > > This is round 4 of the initial bluetooth: separate HSP and HFP
> > > > patch.
> > > >    It includes the review feedback and a global on/off switch
> > > > just in case there's a problem headset with dual HFP/HSP but
> > > > non-working HFP.   This one now includes a proper rfcomm
> > > > negotiation (see patch 3).  I've finally figured out a bug in
> > > > the rfcomm negotiation that was causing issues with my LG 900
> > > > headset, so I think it's now working for everything (but
> > > > testing would be welcome).
> > > > 
> > > > James Bottomley (3):
> > > >     bluetooth: use consistent profile names
> > > >     bluetooth: separate HSP and HFP
> > > >     bluetooth: add correct HFP rfcomm negotiation
> > > > 
> > > >    src/modules/bluetooth/backend-native.c          | 168
> > > > +++++++++++++++++++++---
> > > >    src/modules/bluetooth/backend-ofono.c           |   4 +-
> > > >    src/modules/bluetooth/bluez5-util.c             |  46 +++++-
> > > > -
> > > >    src/modules/bluetooth/bluez5-util.h             |  10 +-
> > > >    src/modules/bluetooth/module-bluetooth-policy.c |   3 +-
> > > >    src/modules/bluetooth/module-bluez5-device.c    | 102
> > > > ++++++++++-
> > > > ---
> > > >    src/modules/bluetooth/module-bluez5-discover.c  |   6 +-
> > > >    7 files changed, 274 insertions(+), 65 deletions(-)
> > > > 
> > > Hello James,
> > > 
> > > thank you for continuing your work. Unfortunately your patch set
> > > collides with running ofono. Currently, with the default of
> > > "headest=auto", the native and the ofono backends are active in
> > > parallel. This is possible because ofono only supports HFP while
> > > PA only supports HSP.
> > > 
> > > If PA starts supporting HFP headsets, this breaks above
> > > assumption and ofono and PA both try to register the
> > > corresponding HFP UUID.
> > > 
> > > To work around the problem, I suggest to disable native HFP
> > > support if headset_backend == HEADSET_BACKEND_AUTO, unless
> > > configured otherwise on the command line.
> > Actually, Pulseaudio already includes an ofono is running check, so
> > the enable should be set to no for backend ofono or backend auto
> > and ofono running, which would enable it in the widest possible set
> > of scenarios.
> > 
> > I can cook up a patch for that, hang on.
> > 
> > James
> 
> This does only work for the special case when PA acts in the
> HSP headset role. In this case, no duplicate UUIDs are registered
> and disabling the profile only needs to be done because otherwise
> PA and ofono would both be listening for incoming SCO connections.

It seems to me that pulse checks the dbus connection to ofono before
deciding on the backend (and therefore deciding what to register), so
as long as pulse finds ofono running, there won't be any duplicate
registrations.

> The case here is different in that a duplicate UUID is registered.
> This means, by the time PA recognizes that ofono is running, ofono
> already tried to register the UUID and failed. That's why you have to
> disable HFP even if ofono is currently not running.

I don't think that can be true if ofono is already running, can it?
 Either ofono registered the HFP UUIDs way earlier or pulse sees ofono
isn't running and registers them.

I don't think requiring the ofono daemon to be running before
pulseaudio is insurmountable.  On my openSUSE system, ofono is started
from systemd and pulse from user login, so this is automatically
satisfied.  I think where pulse is used in system mode, you just have
to tell systemd to start ofono first, which is certainly doable.

The current fly in the ointment is that for a dual HFP/HSP device, we
need to fall back to the HSP profile not simply disable the HFP one,
which requires extra jiggerypokery.

James