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Subject: Re: [PATCHv2] Bluetooth: quirk disabling LE Read Transmit Power
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20211001083412.3078-1-redecorating@protonmail.com>
Date:   Fri, 1 Oct 2021 11:35:16 +0200
Cc:     danielwinkler@google.com, Johan Hedberg <johan.hedberg@intel.com>,
        linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
        regressions@lists.linux.dev, sonnysasaka@chromium.org
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References: <4970a940-211b-25d6-edab-21a815313954@protonmail.com>
 <20210930063106.19881-1-redecorating@protonmail.com>
 <20210930141256.19943-1-redecorating@protonmail.com>
 <FA02CDD7-CFEC-4481-9940-BA95D81FD3F3@holtmann.org>
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 <20211001083412.3078-1-redecorating@protonmail.com>
To:     Orlando Chamberlain <redecorating@protonmail.com>
Precedence: bulk

Hi Orlando,

> The LE Read Transmit Power command is Advertised on some Broadcom
> controlers, but not supported. Using this command breaks Bluetooth
> on the MacBookPro16,1 and iMac20,1. Added a quirk disabling LE Read
> Transmit Power for these devices, based off their common chip id 150.
> 
> Link: https://lore.kernel.org/r/4970a940-211b-25d6-edab-21a815313954@protonmail.com
> Signed-off-by: Orlando Chamberlain <redecorating@protonmail.com>
> ---
> v1->v2: Clarified quirk description
> 
> drivers/bluetooth/btbcm.c   |  4 ++++
> include/net/bluetooth/hci.h | 11 +++++++++++
> net/bluetooth/hci_core.c    |  3 ++-
> 3 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bluetooth/btbcm.c b/drivers/bluetooth/btbcm.c
> index e4182acee488..4ecc50d93107 100644
> --- a/drivers/bluetooth/btbcm.c
> +++ b/drivers/bluetooth/btbcm.c
> @@ -353,6 +353,10 @@ static int btbcm_read_info(struct hci_dev *hdev)
> 		return PTR_ERR(skb);
> 
> 	bt_dev_info(hdev, "BCM: chip id %u", skb->data[1]);
> +
> +	if (skb->data[1] == 150)
> +		set_bit(HCI_QUIRK_BROKEN_READ_TRANSMIT_POWER, &hdev->quirks);
> +
> 	kfree_skb(skb);

I would really prefer to do that via the ACPI table matching in hci_bcm.c and not via some magic chip id check. We actually don’t know how Broadcom assigns their chip ids.

Regards

Marcel