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From: Sven Peter <sven@svenpeter.dev>
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Subject: Re: [PATCH v3] Bluetooth: Fix Bluetooth for BCM4377 on T2 Intel MacBooks
Date: Thu, 4 Jan 2024 08:50:19 +0100
Message-Id: <86B7DC5B-B25A-4D55-BBC7-A1C3EE8AC703@svenpeter.dev>
References: <MA0P287MB021769BC136ED0B947683709B867A@MA0P287MB0217.INDP287.PROD.OUTLOOK.COM>
Cc: Johan Hovold <johan@kernel.org>, Paul Menzel <pmenzel@molgen.mpg.de>,
 Felix Zhang <mrman@mrman314.tech>, linux-bluetooth@vger.kernel.org,
 stable@vger.kernel.org, Johan Hovold <johan+linaro@kernel.org>,
 Hector Martin <marcan@marcan.st>, Bagas Sanjaya <bagasdotme@gmail.com>,
 Alyssa Rosenzweig <alyssa@rosenzweig.io>,
 Marcel Holtmann <marcel@holtmann.org>,
 Johan Hedberg <johan.hedberg@gmail.com>,
 Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
 Orlando Chamberlain <orlandoch.dev@gmail.com>, kekrby@gmail.com,
 admin@kodeit.net, Janne Grunau <j@jannau.net>, asahi@lists.linux.dev,
 linux-kernel@vger.kernel.org
In-Reply-To: <MA0P287MB021769BC136ED0B947683709B867A@MA0P287MB0217.INDP287.PROD.OUTLOOK.COM>
To: Aditya Garg <gargaditya08@live.com>


>=20
> On 4. Jan 2024, at 08:47, Aditya Garg <gargaditya08@live.com> wrote:
>=20
> =EF=BB=BF
>=20
>> On 28-Dec-2023, at 5:41=E2=80=AFPM, Johan Hovold <johan@kernel.org> wrote=
:
>>=20
>> =EF=BB=BFOn Thu, Dec 28, 2023 at 10:46:57AM +0100, Sven Peter wrote:
>>=20
>>>>>> On Dec 27, 2023, at 11:30, Johan Hovold <johan@kernel.org> wrote:
>>>=20
>>>>> The commit you tracked this down to restored the original semantics fo=
r
>>>> HCI_QUIRK_USE_BDADDR_PROPERTY, which means that it should only be set
>>>> for devices with an invalid address.
>>>>=20
>>>> The Broadcom BCM4377 driver has so far been setting this flag
>>>> unconditionally which now potentially results in also valid addresses
>>>> being marked as invalid.
>>>>=20
>>>> I've just sent a patch that makes sure to only mark invalid addresses a=
s
>>>> invalid:
>>>>=20
>>>> https://lore.kernel.org/lkml/20231227101003.10534-1-johan+linaro@kernel=
.org/
>>>>=20
>>>> Note however that the flag still needs to be set in case your device
>>>> lacks storage for a unique device address so you cannot simply drop it
>>>> for some device classes as you do below (unless you are certain that
>>>> these devices will always have a valid address).
>>=20
>>> We do know that though.
>>>=20
>>> BCM4377 is present on Apple=E2=80=99s x86 Macs and always has internal s=
torage
>>> for the address. If the board comes up without an address there=E2=80=99=
s nothing
>>> much we can do because the address isn=E2=80=99t provided by ACPI or any=
thing
>>> else and setting the invalid address quirk for that situation seems appr=
opriate.
>>>=20
>>> BCM4378/4387 is present on Apple=E2=80=99s ARM Macs and never has intern=
al storage.
>>> The address is always provided by our bootloader in the device tree.
>>> These should always unconditionally set HCI_QUIRK_USE_BDADDR_PROPERTY
>>> just like this patch does.
>>=20
>> Ok, good, then this patch and the one I posted are mostly equivalent
>> assuming that the BCM4378/4387 return an invalid address during setup.
>>=20
>> This patch may be preferred as it does not need to rely on such
>> assumptions, though.
>>=20
>> Johan
>=20
> So what's the final take on this? Which one is gonna be merged upstream?

I would=E2=80=99ve preferred this one (possibly with a better commit message=
) since it=E2=80=99s more explicit and doesn=E2=80=99t rely on additional as=
sumptions but it looks like Johan=E2=80=99s version was already merged.


Sven