[pulseaudio-discuss] Adding support for bluetooth headsets that only have HFP

[James Bottomley]

On Fri, 2016-08-19 at 20:24 +0300, Tanu Kaskinen wrote:
> On Thu, 2016-08-18 at 07:51 -0700, James Bottomley wrote:
> > I recently switched from a JBL Flip 2 which supports both HSP and
> > HFP
> > to an Ultimate Ears Boom 2 which is HFP only.  Needless to say this
> > currently means that the Ultimate Ears fails to work with 
> > pulseaudio because we only support HSP via the native backend.  The 
> > first thing to note is that we can easily get HFP running in 
> > pulseaudio via a quick hack to switch support from HSP to HFP (see 
> > patch below) because if you don't negotiate protocols on HFP it 
> > looks pretty much like HSP for the audio stream.  Unfortunately, 
> > doing this would break half the headsets out there which only 
> > support HSP, so the hack is for demo purposes only.
> > 
> > I think the fix is to expose HFP and HSP separately as different
> > pulseaudio profiles.  This would also allow negotiating useful HFP
> > features, like wideband audio, which HSP doesn't support.  It would
> > also mean that people currently using HSP would continue, even if 
> > they had HFP and that headsets which support both will show both in 
> > the PA configuration possibilities.  If people are OK with this 
> > approach, I can produce a patch set.
> 
> I was under the impression that supporting HFP would have to be much
> more complex than that. If that one-line hack really is sufficient 
> for getting audio moving, I think it makes sense to add HFP support 
> to the native backend. I see you already went ahead and produced a 
> more complete patch :) I'll have a look shortly.

I still think something has to be done in the negotiation.  The spec
definitely implies there's a mandatory rfcomm negotiation before you
establish audio links.  I think I've found a device that's more
unforgiving with this (the Boom seems fine to establish audio links
with no negotiation), so I'll complete the patch series when I get this
working.

The patch is still more of a demo of "is it OK that the interface
appears like this" than a "this works for all known devices apply it".

James