Re: [PATCH] Bluetooth: hci_sync: use HCI_CMD_TIMEOUT for PA sync commands

[Yang Li]

Hi Luiz
> [ EXTERNAL EMAIL ]
>
> Hi Yang,
>
> On Thu, Jan 8, 2026 at 1:03 AM Yang Li via B4 Relay
> <devnull+yang.li.amlogic.com@xxxxxxxxxx> wrote:
> > From: Yang Li <yang.li@xxxxxxxxxxx>
> >
> > PA sync HCI commands incorrectly use conn->conn_timeout, which defaults
> > to 20s and is too long. If the PA Sync Established event is not
> > received, the command remains pending and causes userspace timeouts.
> Im pretty sure this is impossible scenario with bluetooth-next, since
> 1. only one work can be running hci_le_pa_create_sync at time so
> HCI_EV_LE_PA_SYNC_ESTABLISHED cannot be outstanding 2. The
> conn->timeout shall be aligned with socket timeout so perhaps the
> problem is userspace is not setting the socket timeout correctly or
> something.


Well, I got it.

I noticed that BlueZ has a default setting for sync_time with the value 
BT_ISO_SYNC_TIMEOUT=0x07d0 /* 20 secs */.

I would like to know the rationale behind setting it to 20 seconds 
initially. This value seems a bit long to me. Can I directly change this 
value as:

BT_ISO_SYNC_TIMEOUT=0x00C8 /* 2 secs */

> > Signed-off-by: Yang Li <yang.li@xxxxxxxxxxx>
> > ---
> >   net/bluetooth/hci_sync.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> > index f04a90bce4a9..58292b01f062 100644
> > --- a/net/bluetooth/hci_sync.c
> > +++ b/net/bluetooth/hci_sync.c
> > @@ -7159,7 +7159,7 @@ static int hci_le_pa_create_sync(struct hci_dev *hdev, void *data)
> >          if (conn->sid == HCI_SID_INVALID) {
> >                  err = __hci_cmd_sync_status_sk(hdev, HCI_OP_NOP, 0, NULL,
> >                                                 HCI_EV_LE_EXT_ADV_REPORT,
> > -                                              conn->conn_timeout, NULL);
> > +                                              HCI_CMD_TIMEOUT, NULL);
> >                  if (err == -ETIMEDOUT)
> >                          goto done;
> >          }
> > @@ -7187,7 +7187,7 @@ static int hci_le_pa_create_sync(struct hci_dev *hdev, void *data)
> >          err = __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_PA_CREATE_SYNC,
> >                                         sizeof(cp), &cp,
> >                                         HCI_EV_LE_PA_SYNC_ESTABLISHED,
> > -                                      conn->conn_timeout, NULL);
> > +                                      HCI_CMD_TIMEOUT, NULL);
> >          if (err == -ETIMEDOUT)
> >                  __hci_cmd_sync_status(hdev, HCI_OP_LE_PA_CREATE_SYNC_CANCEL,
> >                                        0, NULL, HCI_CMD_TIMEOUT);
> >
> > ---
> > base-commit: bdb9aba465a85122bcba01a6154e237b9843e25b
> > change-id: 20260108-pa_sync_cmd_timeout-ff46f67b5d2a
> >
> > Best regards,
> > --
> > Yang Li <yang.li@xxxxxxxxxxx>
>
> --
> Luiz Augusto von Dentz