Re: [PATCH] Bluetooth: hci_event: Add support for handling LE BIG Sync Lost event

[Yang Li]

Hi,
> [ EXTERNAL EMAIL ]
>
> Dear Li,
>
>
> Thank you for your patch.
>
>
> Am 24.06.25 um 07:20 schrieb Yang Li via B4 Relay:
> > From: Yang Li <yang.li@xxxxxxxxxxx>
> >
> > When the BIS source stops, the controller sends an LE BIG Sync Lost
> > event (subevent 0x1E). Currently, this event is not handled, causing
> > the BIS stream to remain active in BlueZ and preventing recovery.
>
> How can this situation be emulated to test your patch?


My test environment is as follows:

I connect a Pixel phone to the DUT and use the phone as a BIS source for 
audio sharing. The DUT synchronizes with the audio stream from the phone.
After I pause the music on the phone, the DUT's controller reports a BIG 
Sync Lost event.

I believe this scenario can also be reproduced using the isotest tool. 
For example:
 - Use Board A as the BIS source.
 - Use Board B to execute scan on.
 - Once Board B synchronizes with Board A, exit isotest on Board A.
 - Board B should then receive the BIG Sync Lost event as well.

Additionally, the following BlueZ patch is required for proper handling 
of this event:
https://lore.kernel.org/all/20250624-bap_for_big_sync_lost-v1-1-0df90a0f55d0@xxxxxxxxxxx/


> > Signed-off-by: Yang Li <yang.li@xxxxxxxxxxx>
> > ---
> >   include/net/bluetooth/hci.h |  6 ++++++
> >   net/bluetooth/hci_event.c   | 23 +++++++++++++++++++++++
> >   2 files changed, 29 insertions(+)
> >
> > diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> > index 82cbd54443ac..48389a64accb 100644
> > --- a/include/net/bluetooth/hci.h
> > +++ b/include/net/bluetooth/hci.h
> > @@ -2849,6 +2849,12 @@ struct hci_evt_le_big_sync_estabilished {
> >       __le16  bis[];
> >   } __packed;
> >
> > +#define HCI_EVT_LE_BIG_SYNC_LOST 0x1e
> > +struct hci_evt_le_big_sync_lost {
> > +     __u8    handle;
> > +     __u8    reason;
> > +} __packed;
> > +
> >   #define HCI_EVT_LE_BIG_INFO_ADV_REPORT      0x22
> >   struct hci_evt_le_big_info_adv_report {
> >       __le16  sync_handle;
> > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > index 66052d6aaa1d..730deaf1851f 100644
> > --- a/net/bluetooth/hci_event.c
> > +++ b/net/bluetooth/hci_event.c
> > @@ -7026,6 +7026,24 @@ static void 
> > hci_le_big_sync_established_evt(struct hci_dev *hdev, void *data,
> >       hci_dev_unlock(hdev);
> >   }
> >
> > +static void hci_le_big_sync_lost_evt(struct hci_dev *hdev, void *data,
> > +                                         struct sk_buff *skb)
> > +{
> > +     struct hci_evt_le_big_sync_lost *ev = data;
> > +     struct hci_conn *conn;
> > +
> > +     bt_dev_dbg(hdev, "BIG Sync Lost: big_handle 0x%2.2x", ev->handle);
> > +
> > +     hci_dev_lock(hdev);
> > +
> > +     list_for_each_entry(conn, &hdev->conn_hash.list, list) {
> > +             if (test_bit(HCI_CONN_BIG_SYNC, &conn->flags))
> > +                     hci_disconn_cfm(conn, HCI_ERROR_REMOTE_USER_TERM);
> > +     }
> > +
> > +     hci_dev_unlock(hdev);
> > +}
> > +
> >   static void hci_le_big_info_adv_report_evt(struct hci_dev *hdev, 
> > void *data,
> >                                          struct sk_buff *skb)
> >   {
> > @@ -7149,6 +7167,11 @@ static const struct hci_le_ev {
> >                    hci_le_big_sync_established_evt,
> >                    sizeof(struct hci_evt_le_big_sync_estabilished),
> >                    HCI_MAX_EVENT_SIZE),
> > +     /* [0x1e = HCI_EVT_LE_BIG_SYNC_LOST] */
> > +     HCI_LE_EV_VL(HCI_EVT_LE_BIG_SYNC_LOST,
> > +                  hci_le_big_sync_lost_evt,
> > +                  sizeof(struct hci_evt_le_big_sync_lost),
> > +                  HCI_MAX_EVENT_SIZE),
> >       /* [0x22 = HCI_EVT_LE_BIG_INFO_ADV_REPORT] */
> >       HCI_LE_EV_VL(HCI_EVT_LE_BIG_INFO_ADV_REPORT,
> >                    hci_le_big_info_adv_report_evt,
>
> Kind regards,
>
> Paul