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

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Message-Id: <9308033b-971f-4cbf-9443-d41a3f09ac61@app.fastmail.com>
Date:   Tue, 14 Nov 2023 09:35:27 +0100
From:   "Janne Grunau" <j@...nau.net>
To:     "Aditya Garg" <gargaditya08@...e.com>,
        "Hector Martin" <marcan@...can.st>,
        "Sven Peter" <sven@...npeter.dev>,
        "Alyssa Rosenzweig" <alyssa@...enzweig.io>,
        "marcel@...tmann.org" <marcel@...tmann.org>,
        "johan.hedberg@...il.com" <johan.hedberg@...il.com>,
        "luiz.dentz@...il.com" <luiz.dentz@...il.com>
Cc:     "Orlando Chamberlain" <orlandoch.dev@...il.com>,
        "Kerem Karabay" <kekrby@...il.com>,
        "Aun-Ali Zaidi" <admin@...eit.net>,
        "Asahi Linux" <asahi@...ts.linux.dev>,
        LKML <linux-kernel@...r.kernel.org>,
        "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>
Subject: Re: [REGRESSION] Bluetooth is not working on Macs with BCM4377 chip starting
 from kernel 6.5

Hej,

On Mon, Nov 13, 2023, at 21:57, 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.

There could be a possible regression in kernel 6.4 and later affecting Bluetooth low energy on bcm4377 devices specifically.  288c90224eec ("Bluetooth: Enable all supported LE PHY by default") broke BLE connections on bcm4378 and bcm4387. I did not find any reports about broken BLE on bcm4377 so I marked only bcm4378 and bcm4387 as broken with Coded Phy in 41e9cdea9c4a ("Bluetooth: hci_bcm4377: Mark bcm4378/bcm4387 as BROKEN_LE_CODED")

If  BLE devices like Logitech keyboards/mice are affected (mostly during pairing) it would be worth testing the change below (against v6.7-rc or stable releases):

diff --git a/drivers/bluetooth/hci_bcm4377.c b/drivers/bluetooth/hci_bcm4377.c
index a61757835695..bc8398cde3c3 100644
--- a/drivers/bluetooth/hci_bcm4377.c
+++ b/drivers/bluetooth/hci_bcm4377.c
@@ -2453,6 +2453,7 @@ static const struct bcm4377_hw bcm4377_hw_variants[] = {
                .bar0_window2 = 0x1810c000,
                .disable_aspm = true,
                .broken_ext_scan = true,
+               .broken_le_coded = true,
                .send_ptb = bcm4377_send_ptb,
        },
 
This  should affect 6.4.8 as well so might be unrelated to the reported issue.

Janne