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SubjectRe: [PATCHv2] Bluetooth: quirk disabling LE Read Transmit Power
Date


> On 06-Nov-2021, at 5:19 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Sat, Nov 06, 2021 at 09:41:28AM +0000, Aditya Garg wrote:
>>
>>
>>> On 06-Nov-2021, at 3:17 AM, Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
>>>
>>> Hi Orlando,
>>>
>>> On Fri, Oct 1, 2021 at 1:56 AM Orlando Chamberlain
>>> <redecorating@protonmail.com> wrote:
>>>>
>>>> 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);
>>>>
>>>> /* Read Controller Features */
>>>> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
>>>> index b80415011dcd..6da9bd6b7259 100644
>>>> --- a/include/net/bluetooth/hci.h
>>>> +++ b/include/net/bluetooth/hci.h
>>>> @@ -246,6 +246,17 @@ enum {
>>>> * HCI after resume.
>>>> */
>>>> HCI_QUIRK_NO_SUSPEND_NOTIFIER,
>>>> +
>>>> + /* When this quirk is set, LE Read Transmit Power is disabled.
>>>> + * This is mainly due to the fact that the HCI LE Read Transmit
>>>> + * Power command is advertised, but not supported; these
>>>> + * controllers often reply with unknown command and need a hard
>>>> + * reset.
>>>> + *
>>>> + * This quirk can be set before hci_register_dev is called or
>>>> + * during the hdev->setup vendor callback.
>>>> + */
>>>> + HCI_QUIRK_BROKEN_READ_TRANSMIT_POWER,
>>>> };
>>>>
>>>> /* HCI device flags */
>>>> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
>>>> index 8a47a3017d61..9a23fe7c8d67 100644
>>>> --- a/net/bluetooth/hci_core.c
>>>> +++ b/net/bluetooth/hci_core.c
>>>> @@ -742,7 +742,8 @@ static int hci_init3_req(struct hci_request *req, unsigned long opt)
>>>> hci_req_add(req, HCI_OP_LE_READ_ADV_TX_POWER, 0, NULL);
>>>> }
>>>>
>>>> - if (hdev->commands[38] & 0x80) {
>>>> + if (hdev->commands[38] & 0x80 &&
>>>> + !test_bit(HCI_QUIRK_BROKEN_READ_TRANSMIT_POWER, &hdev->quirks)) {
>>>> /* Read LE Min/Max Tx Power*/
>>>> hci_req_add(req, HCI_OP_LE_READ_TRANSMIT_POWER,
>>>> 0, NULL);
>>>> --
>>>> 2.33.0
>>>
>>> Nowadays it is possible to treat errors such like this on a per
>>> command basis (assuming it is not essential for the init sequence):
>>>
>>> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
>>> index 979da5179ff4..f244f42cc609 100644
>>> --- a/include/net/bluetooth/hci.h
>>> +++ b/include/net/bluetooth/hci.h
>>> @@ -551,6 +551,7 @@ enum {
>>> #define HCI_LK_AUTH_COMBINATION_P256 0x08
>>>
>>> /* ---- HCI Error Codes ---- */
>>> +#define HCI_ERROR_UNKNOWN_CMD 0x01
>>> #define HCI_ERROR_UNKNOWN_CONN_ID 0x02
>>> #define HCI_ERROR_AUTH_FAILURE 0x05
>>> #define HCI_ERROR_PIN_OR_KEY_MISSING 0x06
>>> diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
>> This diff cannot be applied to stable 5.15. Could you provide a patch capable of being applied to stable.
>
> That is not needed until a patch is in Linus's tree. Why do you need it
> earlier?
>
Well not an emergency, but the issue of Bluetooth not working on some Apple Macs has been there for a long time. BTW, will this patch be there in Linus’s tree in the coming days?
> thanks,
>
> greg k-h

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