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From: Pauli Virtanen <pav@iki.fi>
To: "Michał Kępień" <kernel@kempniu.pl>
Cc: linux-bluetooth <linux-bluetooth@vger.kernel.org>
Subject: Re: [PATCH] Bluetooth: btusb: check SCO MTU before enabling USB ALT 3 for WBS
Date: Thu, 22 Jul 2021 17:26:07 +0300	[thread overview]
Message-ID: <f32df70b9aaccfbb471a6305c5b4884ae14dede3.camel@iki.fi> (raw)
In-Reply-To: <YPly1RR8V33T3odj@larwa.hq.kempniu.pl>

Hi Michał,

to, 2021-07-22 kello 15:29 +0200, Michał Kępień kirjoitti:
> Thank you for your work on this patch!
> 
> > Some USB BT adapters don't satisfy the MTU requirement mentioned in
> > commit e848dbd364ac ("Bluetooth: btusb: Add support USB ALT 3 for WBS")
> > and have ALT 3 setting that produces no/garbled audio. Check that the MTU
> > condition is satisfied, and fall back to ALT 1 if not.
> > 
> > Tested with USB adapters (mtu<72, produce sound only with ALT1)
> > BCM20702A1 0b05:17cb, CSR8510A10 0a12:0001, and (mtu>=72, ALT3)
> > RTL8761BU 0bda:8771, Intel AX200 8087:0029 (after disabling ALT6).
> 
> Commit e848dbd364aca44c9d23c04bef964fab79e2b34f causes garbled mSBC
> audio on my Bluetooth adapter (8087:0a2b), so I gave your patch a try.
> 
> Unfortunately, the patch in its current shape does not seem to be enough
> to fix things for this adapter, which reports an SCO MTU of 96 bytes and
> produces garbled mSBC audio with ALT 3.
> 
> For the record, reverting e848dbd364aca44c9d23c04bef964fab79e2b34f on
> top of v5.14-rc2 makes mSBC work again with my adapter.
> 
> I am no Bluetooth expert, but I will be happy to perform any additional
> debugging and/or testing.

Thanks for testing! What userspace software did you use? Pulseaudio at
least I think had assumption that mtu <= 60, which breaks here
(Pipewire works, don't know about bluez-alsa). If otherwise, maybe it
then needs also the manufacturer flag.

Best,
Pauli


  reply	other threads:[~2021-07-22 14:26 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-16 17:58 [PATCH] Bluetooth: btusb: check SCO MTU before enabling USB ALT 3 for WBS Pauli Virtanen
2021-07-16 19:16 ` bluez.test.bot
2021-07-17 13:34 ` [PATCH] " Joseph Hwang
2021-07-21 15:40   ` Pauli Virtanen
2021-07-22 10:28     ` Hilda Wu
2021-07-20  9:15 ` Pasi Kärkkäinen
2021-07-22 13:29 ` Michał Kępień
2021-07-22 14:26   ` Pauli Virtanen [this message]
2021-07-22 14:42     ` Michał Kępień
2021-07-23 10:07 ` [PATCH v2] Bluetooth: btusb: check conditions " Pauli Virtanen
2021-07-23 12:19   ` Marcel Holtmann
2021-07-25  5:47     ` Michał Kępień
2021-08-10 16:48     ` Pasi Kärkkäinen
2021-08-10 18:37       ` Luiz Augusto von Dentz
2021-07-26 18:02 ` [PATCH v3] " Pauli Virtanen
2021-07-27  2:11   ` [v3] " bluez.test.bot
2021-07-30 12:35   ` [PATCH v3] " Pasi Kärkkäinen

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