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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Tue, 30 Jun 2020 17:30:44 -0700
Message-ID: <CABBYNZ+xTsRKFHZrjuxCbxR=tWYmGr79SaLsKEbscuCt3zobPw@mail.gmail.com>
Subject: Re: [Bluez PATCH v1] device - If HFP is supported, ignore HSP
To:     Yu Liu <yudiliu@google.com>
Cc:     "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>,
        Hsin-Yu Chao <hychao@google.com>,
        Sonny Sasaka <sonnysasaka@chromium.org>
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Hi Yu Liu,

On Tue, Jun 30, 2020 at 3:55 PM Yu Liu <yudiliu@google.com> wrote:
>
> From: Hsin-Yu Chao <hychao@google.com>
>
> For a BT headset that supports both HSP and HFP, BlueZ creates
> service instances for these two profiles and connects them.
> It's uncertain that which of HSP and HFP eventually get connected
> and being used for SCO audio. And we start observing some problem
> because of this uncertainty:
>
> - For headset that supports WBS, we need HFP connect for codec
> negotiation. If HSP connects but not HFP, WBS cannot be used.

We should probably have a way to detect when one or the other is
connected and then don't attempt to connect again since they would
likely conflict when it comes to connecting SCO, that said is your
system setting AutoConnect for both HSP and HFP?

> - For WH-1000XM3, if BlueZ ever initiated HFP connection but failed,
> headset won't have working SCO audio even HSP is connected.

Hmm I guess this will need to treated separately, not sure if we can
exclude HSP to be connected once HFP fails, but then again I think the
system should not have them both set to be Auto Connected, HSP most
likely should only be set as as a fallback if HFP is not supported.

> Fix this at when device probes services, if HFP is in the uuid list,
> don't bother create one for HSP.
>
> Reviewed-by: Sonny Sasaka <sonnysasaka@chromium.org>
> ---
>
> Changes in v1:
> - Initial change
>
>  src/device.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/src/device.c b/src/device.c
> index 7b0eb256e..4036bfd81 100644
> --- a/src/device.c
> +++ b/src/device.c
> @@ -4370,6 +4370,11 @@ static struct btd_service *probe_service(struct btd_device *device,
>         if (!device_match_profile(device, profile, uuids))
>                 return NULL;
>
> +       /* If device supports HFP, don't bother create service for HSP. */
> +       if (g_slist_find_custom(uuids, HFP_HS_UUID, bt_uuid_strcmp) &&
> +               bt_uuid_strcmp(profile->remote_uuid, HSP_HS_UUID) == 0)
> +               return NULL;
> +
>         l = find_service_with_profile(device->services, profile);
>         if (l)
>                 return l->data;
> --
> 2.27.0.212.ge8ba1cc988-goog
>


-- 
Luiz Augusto von Dentz