[pulseaudio-discuss] [PATCH v5 5/7] bluetooth: Auto recover if profile is 'off'

[Luiz Augusto von Dentz]

Hi Tanu,

On Thu, May 4, 2017 at 3:29 PM, Tanu Kaskinen <tanuk at iki.fi> wrote:
> On Thu, 2017-05-04 at 12:58 +0300, Luiz Augusto von Dentz wrote:
>> From: Luiz Augusto von Dentz <luiz.von.dentz at intel.com>
>>
>> This means something went wrong, which in case of ofono backend it is
>> probably due to the profile not connecting immediately, but it can be
>> safely restored in that case the transport is playing which means the
>> profile has recovered connectivity.
>> ---
>>  src/modules/bluetooth/module-bluez5-device.c | 8 +++++++-
>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/modules/bluetooth/module-bluez5-device.c b/src/modules/bluetooth/module-bluez5-device.c
>> index a96da17..2f0ec97 100644
>> --- a/src/modules/bluetooth/module-bluez5-device.c
>> +++ b/src/modules/bluetooth/module-bluez5-device.c
>> @@ -2060,8 +2060,14 @@ static pa_hook_result_t transport_state_changed_cb(pa_bluetooth_discovery *y, pa
>>      if (t == u->transport && t->state <= PA_BLUETOOTH_TRANSPORT_STATE_DISCONNECTED)
>>          pa_assert_se(pa_card_set_profile(u->card, pa_hashmap_get(u->card->profiles, "off"), false) >= 0);
>>
>> -    if (t->device == u->device)
>> +    if (t->device == u->device) {
>> +        /* Auto recover from errors causing the profile to be set to off */
>> +        if (u->profile == PA_BLUETOOTH_PROFILE_OFF && t->state == PA_BLUETOOTH_TRANSPORT_STATE_PLAYING) {
>> +            pa_log_debug("Switching to profile %s", pa_bluetooth_profile_to_string(t->profile));
>> +            pa_assert_se(pa_card_set_profile(u->card, pa_hashmap_get(u->card->profiles, pa_bluetooth_profile_to_string(t->profile)), false) >= 0);
>
> Regarding the assertion, how do you know that the card profile switch
> will always succeed? Is there no IO involved? If you somehow know that
> it will always succeed, there should be a comment explaining how you
> know that.

The playing state should guarantee the fd is available, so there
shouldn't be any problem in this regard.

> I know there are already assertions when switching to the off profile,
> but that's a special profile - activating it should never fail.
>
> This change seems dubious in another way too. So far we've kept all
> automatic profile switch code out of module-bluez5-device (apart from
> switches to "off" when things fail). Automatic switching is handled by
> module-bluetooth-policy instead. If I understood correctly, this is a
> fix for a situation where we already tried to switch to a profile, but
> it failed first. The code is lacking any checks that would do the
> profile change only if there really was a prior profile switch attempt.

It is exactly to counter the profiles switching 'off' which is done in
the device itself, we could of course move this to policy as well
though. Note that in most cases it is better to switch to a working
profile than 'off' since that for sure won't render anything.

> --
> Tanu
>
> https://www.patreon.com/tanuk
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-- 
Luiz Augusto von Dentz