linux-kernel - Re: [PATCH v3] Bluetooth: Fix Bluetooth for BCM4377 on T2 Intel MacBooks

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Message-Id: <86B7DC5B-B25A-4D55-BBC7-A1C3EE8AC703@svenpeter.dev>
Date: Thu, 4 Jan 2024 08:50:19 +0100
From: Sven Peter <sven@...npeter.dev>
To: Aditya Garg <gargaditya08@...e.com>
Cc: Johan Hovold <johan@...nel.org>, Paul Menzel <pmenzel@...gen.mpg.de>,
 Felix Zhang <mrman@...an314.tech>, linux-bluetooth@...r.kernel.org,
 stable@...r.kernel.org, Johan Hovold <johan+linaro@...nel.org>,
 Hector Martin <marcan@...can.st>, Bagas Sanjaya <bagasdotme@...il.com>,
 Alyssa Rosenzweig <alyssa@...enzweig.io>,
 Marcel Holtmann <marcel@...tmann.org>,
 Johan Hedberg <johan.hedberg@...il.com>,
 Luiz Augusto von Dentz <luiz.dentz@...il.com>,
 Orlando Chamberlain <orlandoch.dev@...il.com>, kekrby@...il.com,
 admin@...eit.net, Janne Grunau <j@...nau.net>, asahi@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] Bluetooth: Fix Bluetooth for BCM4377 on T2 Intel MacBooks


> 
> On 4. Jan 2024, at 08:47, Aditya Garg <gargaditya08@...e.com> wrote:
> 
> 
> 
>> On 28-Dec-2023, at 5:41 PM, Johan Hovold <johan@...nel.org> wrote:
>> 
>> On Thu, Dec 28, 2023 at 10:46:57AM +0100, Sven Peter wrote:
>> 
>>>>>> On Dec 27, 2023, at 11:30, Johan Hovold <johan@...nel.org> wrote:
>>> 
>>>>> The commit you tracked this down to restored the original semantics for
>>>> HCI_QUIRK_USE_BDADDR_PROPERTY, which means that it should only be set
>>>> for devices with an invalid address.
>>>> 
>>>> The Broadcom BCM4377 driver has so far been setting this flag
>>>> unconditionally which now potentially results in also valid addresses
>>>> being marked as invalid.
>>>> 
>>>> I've just sent a patch that makes sure to only mark invalid addresses as
>>>> invalid:
>>>> 
>>>> https://lore.kernel.org/lkml/20231227101003.10534-1-johan+linaro@kernel.org/
>>>> 
>>>> 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).
>> 
>>> We do know that though.
>>> 
>>> BCM4377 is present on Apple’s x86 Macs and always has internal storage
>>> for the address. If the board comes up without an address there’s nothing
>>> much we can do because the address isn’t provided by ACPI or anything
>>> else and setting the invalid address quirk for that situation seems appropriate.
>>> 
>>> BCM4378/4387 is present on Apple’s ARM Macs and never has internal 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.
>> 
>> Ok, good, then this patch and the one I posted are mostly equivalent
>> assuming that the BCM4378/4387 return an invalid address during setup.
>> 
>> This patch may be preferred as it does not need to rely on such
>> assumptions, though.
>> 
>> Johan
> 
> So what's the final take on this? Which one is gonna be merged upstream?

I would’ve preferred this one (possibly with a better commit message) since it’s more explicit and doesn’t rely on additional assumptions but it looks like Johan’s version was already merged.


Sven