Re: [PATCHv2] Bluetooth: quirk disabling LE Read Transmit Power

From: Greg KH
Date: Sun Nov 07 2021 - 03:35:31 EST


On Sat, Nov 06, 2021 at 05:27:27PM +0000, Aditya Garg wrote:
>
>
> > On 06-Nov-2021, at 5:19 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxx> wrote:
> >>>
> >>> Hi Orlando,
> >>>
> >>> On Fri, Oct 1, 2021 at 1:56 AM Orlando Chamberlain
> >>> <redecorating@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx
> >>>> Signed-off-by: Orlando Chamberlain <redecorating@xxxxxxxxxxxxxx>
> >>>> ---
> >>>> 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?

That is up to the bluetooth maintainers, they have to accept it first.

thanks,

greg k-h