Hi Sathish, >>>>> For msbc encoded audio stream over usb transport, btusb driver >>>>> to be set to alternate settings 6 as per BT core spec 5.0. This >>>>> done from hci_sync_conn_complete_evt. The type of air mode is known >>>>> during this event. For this reason the btusb is to be notifed >>>>> about the TRANSPARENT air mode and the ALT setting 6 is selected. >>>>> The changes are made considering some discussion over the similar >>>>> patch submitted earlier from Kuba Pawlak(link below) >>>>> https://www.spinics.net/lists/linux-bluetooth/msg64577.html >>>>> >>>>> Signed-off-by: Sathish Narasimman <sathish.narasimman@xxxxxxxxx> >>>>> --- >>>>> drivers/bluetooth/btusb.c | 95 >>>>> +++++++++++++++++++++++++-------------------- >>>>> include/net/bluetooth/hci.h | 1 + >>>>> net/bluetooth/hci_event.c | 5 +++ >>>>> 3 files changed, 59 insertions(+), 42 deletions(-) >>>>> >>>>> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c >>>>> index cd2e5cf..ae924b6 100644 >>>>> --- a/drivers/bluetooth/btusb.c >>>>> +++ b/drivers/bluetooth/btusb.c >>>>> @@ -1390,18 +1390,6 @@ static int btusb_send_frame(struct hci_dev *hdev, >>>>> struct sk_buff *skb) >>>>> return -EILSEQ; >>>>> } >>>>> >>>>> -static void btusb_notify(struct hci_dev *hdev, unsigned int evt) >>>>> -{ >>>>> - struct btusb_data *data = hci_get_drvdata(hdev); >>>>> - >>>>> - BT_DBG("%s evt %d", hdev->name, evt); >>>>> - >>>>> - if (hci_conn_num(hdev, SCO_LINK) != data->sco_num) { >>>>> - data->sco_num = hci_conn_num(hdev, SCO_LINK); >>>>> - schedule_work(&data->work); >>>>> - } >>>>> -} >>>>> - >>>>> static inline int __set_isoc_interface(struct hci_dev *hdev, int >>>>> altsetting) >>>>> { >>>>> struct btusb_data *data = hci_get_drvdata(hdev); >>>>> @@ -1445,6 +1433,58 @@ static inline int __set_isoc_interface(struct >>>>> hci_dev *hdev, int altsetting) >>>>> return 0; >>>>> } >>>>> >>>>> +static void bt_switch_alt_setting(struct hci_dev *hdev, int new_alts) >>>>> +{ >>>>> + struct btusb_data *data = hci_get_drvdata(hdev); >>>>> + >>>>> + if (data->isoc_altsetting != new_alts) { >>>>> + unsigned long flags; >>>>> + >>>>> + clear_bit(BTUSB_ISOC_RUNNING, &data->flags); >>>>> + usb_kill_anchored_urbs(&data->isoc_anchor); >>>>> + >>>>> + /* When isochronous alternate setting needs to be >>>>> + * changed, because SCO connection has been added >>>>> + * or removed, a packet fragment may be left in the >>>>> + * reassembling state. This could lead to wrongly >>>>> + * assembled fragments. >>>>> + * >>>>> + * Clear outstanding fragment when selecting a new >>>>> + * alternate setting. >>>>> + */ >>>>> + spin_lock_irqsave(&data->rxlock, flags); >>>>> + kfree_skb(data->sco_skb); >>>>> + data->sco_skb = NULL; >>>>> + spin_unlock_irqrestore(&data->rxlock, flags); >>>>> + >>>>> + if (__set_isoc_interface(hdev, new_alts) < 0) >>>>> + return; > If controller does not support ALT 6. above function will return negative. > will take care of falling back to ALT 2. >>>>> + } >>>>> + if (!test_and_set_bit(BTUSB_ISOC_RUNNING, &data->flags)) { >>>>> + if (btusb_submit_isoc_urb(hdev, GFP_KERNEL) < 0) >>>>> + clear_bit(BTUSB_ISOC_RUNNING, &data->flags); >>>>> + else >>>>> + btusb_submit_isoc_urb(hdev, GFP_KERNEL); >>>>> + } >>>>> +} >>>>> + >>>>> +static void btusb_notify(struct hci_dev *hdev, unsigned int evt) >>>>> +{ >>>>> + struct btusb_data *data = hci_get_drvdata(hdev); >>>>> + >>>>> + BT_DBG("%s evt %d", hdev->name, evt); >>>>> + >>>>> + if (hci_conn_num(hdev, SCO_LINK) != data->sco_num) { >>>>> + data->sco_num = hci_conn_num(hdev, SCO_LINK); >>>>> + schedule_work(&data->work); >>>>> + } >>>>> + >>>>> + if (evt == HCI_NOTIFY_AIR_MODE_TRANSP) { >>>>> + /* Alt setting 6 is for msbc encoded audio channel */ >>>>> + bt_switch_alt_setting(hdev, 6); >>>> >>>> Have you checked that this works on older controllers? I suppose those >>>> don't have alt_set 6. >>> >>> I took the reference from the core spec 5, Vol 4, Part B, Table 2.1 >>> For USB transport the ALT setting 6 should be used for one msbc voice >>> channel. >>> Yes, for the controllers that does not support ALT setting 6. this patch >>> will not work. >> >> It _must_ keep working with controller that don't support such >> setting, there is no option on that, so there should be a way to just >> read what supported alt settings that are supported and fallback if 6 >> is not supported. >> > If we trying to set to ALT SET 6 and controller does not support. in > btusb.c __set_isoc_interface function > will through error and returns negative if fails to set. So the error > check was available already. > I need to take care of returning to ALT Setting 2 if controller fails > to set ALT 6. > This can be done. will update the patch. please take a look into patch > v2 where the 7.5ms time interval is maintained. we are not doing try-and-error here. In probe() do a proper enumeration of the alternate settings and check if setting 6 is available. Regards Marcel
