Re: [REGRESSION] Bluetooth is not working on Macs with BCM4377 chip starting from kernel 6.5

From: Hector Martin <marcan@marcan.st>
To: Aditya Garg <gargaditya08@live.com>,
	Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Sven Peter <sven@svenpeter.dev>,
	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>,
	Kerem Karabay <kekrby@gmail.com>,
	Aun-Ali Zaidi <admin@kodeit.net>,
	Asahi Linux Mailing List <asahi@lists.linux.dev>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Bluetooth <linux-bluetooth@vger.kernel.org>
Subject: Re: [REGRESSION] Bluetooth is not working on Macs with BCM4377 chip starting from kernel 6.5
Date: Tue, 14 Nov 2023 16:58:36 +0900	[thread overview]
Message-ID: <e2909986-34b5-3ae2-cf5c-a1f8c46a1e0a@marcan.st> (raw)
In-Reply-To: <88fcc70e-9f4b-eeb9-d826-03fa4c40e7c3@marcan.st>

On 14/11/2023 15.59, Hector Martin wrote:
> On 14/11/2023 15.23, Aditya Garg wrote:
>>
>>
>>> On 14-Nov-2023, at 5:01 AM, Bagas Sanjaya <bagasdotme@gmail.com> wrote:
>>>
>>> On Mon, Nov 13, 2023 at 08:57:35PM +0000, Aditya Garg wrote:
>>>> Starting from kernel 6.5, a regression in the kernel is causing Bluetooth to not work on T2 Macs with BCM4377 chip.
>>>>
>>>> Journalctl of kernel 6.4.8 which has Bluetooth working is given here: https://pastebin.com/u9U3kbFJ
>>>>
>>>> Journalctl of kernel 6.5.2, which has Bluetooth broken is given here: https://pastebin.com/aVHNFMRs
>>>>
>>>> Also, the bug hasn’t been fixed even in 6.6.1, as reported by users.
>>>
>>> Can you bisect this regression please?
>>
>> Since I don't have access to this hardware, it's not possible for me to bisect this regression. Let's hope someone is able to do so though.
> 
> It's not a regression, it was always broken. I'm sending a patch.
> 
> - Hector

You are quite likely conflating two problems. The ubsan issue you quoted
was always there and the patch I just sent fixes it, but it almost
certainly always worked fine in practice without ubsan.

The Bluetooth problem you are referring to is likely *specific to
Bluetooth LE devices* and the regression was introduced by 288c90224e
and fixed by 41e9cdea9c, which is also in 6.5.11 and 6.6.1.

If Bluetooth is broken in *some other way* in 6.6.1 then we need a
proper report or a bisect. Your logs don't show any issues other than
the ubsan noise, which is not a regression.

- Hector