Re: [Bluez-devel] [PATCH] Advertise Telephony service class when device offers headset AG or handsfree AG

["Nick Pelly" <npelly@google.com>]

On Sat, Aug 30, 2008 at 3:04 AM, Marcel Holtmann <marcel@holtmann.org> wrote:
> Hi Nick,
>
>> So I looked at the headset and handsfree spec, they do not require
>> that AG's set the telephony bit. sigh.
>>
>> But I can tell you for a fact that the Nokia 616 carkit will not pair
>> unless you set the telephony bit. That is what triggered this patch.
>
> that looks like a really broken device to me. How can it pass the
> qualification if it mandates that bit. Is PTS setting it by accident.
>
>> We have yet to find a device (and we have tested hundreds now) that is
>> not compatible because of the telephony bit. It is a safe change to
>> make.
>
> Check your patch with PTS headset/handsfree and the IOP part.

Yeah thats worth checking. I can't check until Wednesday when I am
back in the office with the PTS tester. I'll post back results.

> I am not
> sure if we can just enable service bits as we like.
>
> So in case I can be convinced to take this patch, it has to be in a
> separate case statement and with a comment that the Nokia 616 is just a
> plain stupid broken device and that is why we did it. The spec. doesn't
> mandate this.
>
> I also realized that the Nokia 616 might just is lucky in the interop
> department since most phones also implement DUN, FAX or SAP and thus the
> telephony bit is set.
>
> This brings me to another question, why don't you just use the serial
> proxy support we have and point it to one of the multiplexed TTYs of
> your GSM unit. Then you get DUN support and that broken Nokia device
> would also work :)

I wish, but this is not an option for us.

>
> So what about the desktop case that enables HS-AG and HF-AG? Are these
> phones? Does headset profile really mean that you have to be phone. Not
> likely. With the GSM requirements of handsfree, maybe.

Both HSP and HFP are intended for telephony. I can't see any harm in
the desktop case in setting the telephony bit, after all it will let
them work with the Nokia 616.

>
>> So sure, you can reject the patch on the basis that it is not mandated
>> by the specification. But if you care about compatibility then it
>> seems like a good change to make. Especially since you now ignore the
>> service class in hcid.conf so there is no easy way to override.
>
> Even before you had no way to set. The automatic service bit
> manipulation would have overwritten it. You can actually just call out
> to hciconfig if you really wanna overwrite it, but that is a pretty bad
> idea. It gives you more pain than anything else.
>
> Regards
>
> Marcel
>
>
>
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