linux-kernel - Re: [PATCH v3 resend 2/2] btbcm: disable read tx power for affected Macs with the T2 Security chip

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Message-ID: <749EAA1E-3207-4772-8781-4F245E126F21@live.com>
Date:   Mon, 29 Nov 2021 12:01:28 +0000
From:   Aditya Garg <gargaditya08@...e.com>
To:     Marcel Holtmann <marcel@...tmann.org>
CC:     Greg KH <gregkh@...uxfoundation.org>,
        Thorsten Leemhuis <regressions@...mhuis.info>,
        Orlando Chamberlain <redecorating@...tonmail.com>,
        Daniel Winkler <danielwinkler@...gle.com>,
        Johan Hedberg <johan.hedberg@...el.com>,
        "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        "regressions@...ts.linux.dev" <regressions@...ts.linux.dev>,
        "sonnysasaka@...omium.org" <sonnysasaka@...omium.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v3 resend 2/2] btbcm: disable read tx power for affected
 Macs with the T2 Security chip



> On 29-Nov-2021, at 4:33 PM, Marcel Holtmann <marcel@...tmann.org> wrote:
> 
> Hi Aditya,
> 
>> Some Macs with the T2 security chip had Bluetooth not working.
>> To fix it we add DMI based quirks to disable querying of LE Tx power.
>> 
>> Signed-off-by: Aditya Garg <gargaditya08@...e.com>
>> ---
>> drivers/bluetooth/btbcm.c | 40 +++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 40 insertions(+)
>> 
>> diff --git a/drivers/bluetooth/btbcm.c b/drivers/bluetooth/btbcm.c
>> index e4182acee488c5..40f7c9c5cf0a5a 100644
>> --- a/drivers/bluetooth/btbcm.c
>> +++ b/drivers/bluetooth/btbcm.c
>> @@ -8,6 +8,7 @@
>> 
>> #include <linux/module.h>
>> #include <linux/firmware.h>
>> +#include <linux/dmi.h>
>> #include <asm/unaligned.h>
>> 
>> #include <net/bluetooth/bluetooth.h>
>> @@ -343,9 +344,44 @@ static struct sk_buff *btbcm_read_usb_product(struct hci_dev *hdev)
>> 	return skb;
>> }
>> 
>> +static const struct dmi_system_id disable_broken_read_transmit_power[] = {
>> +	{
>> +		 .matches = {
>> +			DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
>> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,1"),
>> +		},
>> +	},
>> +	{
>> +		 .matches = {
>> +			DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
>> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,2"),
>> +		},
>> +	},
>> +	{
>> +		 .matches = {
>> +			DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
>> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,4"),
>> +		},
>> +	},
>> +	{
>> +		 .matches = {
>> +			DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
>> +			DMI_MATCH(DMI_PRODUCT_NAME, "iMac20,1"),
>> +		},
>> +	},
>> +	{
>> +		 .matches = {
>> +			DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
>> +			DMI_MATCH(DMI_PRODUCT_NAME, "iMac20,2"),
>> +		},
>> +	},
>> +	{ }
>> +};
>> +
>> static int btbcm_read_info(struct hci_dev *hdev)
>> {
>> 	struct sk_buff *skb;
>> +	const struct dmi_system_id *dmi_id;
> 
> this variable is not needed.
You want me to replace const struct dmi_system_id *dmi_id; with const struct dmi_system_id or remove it altogether.

>> 
>> 	/* Read Verbose Config Version Info */
>> 	skb = btbcm_read_verbose_config(hdev);
>> @@ -363,6 +399,10 @@ static int btbcm_read_info(struct hci_dev *hdev)
>> 	bt_dev_info(hdev, "BCM: features 0x%2.2x", skb->data[1]);
>> 	kfree_skb(skb);
>> 
>> +	/* Read DMI and disable broken Read LE Min/Max Tx Power */
>> +	if (dmi_first_match(disable_broken_read_transmit_power))
>> +		set_bit(HCI_QUIRK_BROKEN_READ_TRANSMIT_POWER, &hdev->quirks);
>> +
>> 	return 0;
>> }
> 
> Regards
> 
> Marcel
>