Hi Pauli,
On Tue, Mar 4, 2025 at 11:29 AM Luiz Augusto von Dentz
<luiz.dentz@xxxxxxxxx> wrote:
>
> From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
>
> This enables buffer flow control for SCO/eSCO
> (see: Bluetooth Core 6.0 spec: 6.22. Synchronous Flow Control Enable),
> recently this has caused the following problem and is actually a nice
> addition for the likes of Socket TX complete:
>
> < HCI Command: Read Buffer Size (0x04|0x0005) plen 0
> > HCI Event: Command Complete (0x0e) plen 11
> Read Buffer Size (0x04|0x0005) ncmd 1
> Status: Success (0x00)
> ACL MTU: 1021 ACL max packet: 5
> SCO MTU: 240 SCO max packet: 8
> ...
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> < SCO Data TX: Handle 257 flags 0x00 dlen 120
> > HCI Event: Hardware Error (0x10) plen 1
> Code: 0x0a
>
> Fixes: 7fedd3bb6b77 ("Bluetooth: Prioritize SCO traffic")
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
> ---
> include/net/bluetooth/hci.h | 6 ++++++
> include/net/bluetooth/hci_core.h | 1 +
> net/bluetooth/hci_core.c | 28 ++++++++++++++++++++++++++++
> net/bluetooth/hci_sync.c | 23 +++++++++++++++++++++++
> 4 files changed, 58 insertions(+)
>
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index b99818df8ee7..70169533c940 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -448,6 +448,7 @@ enum {
> HCI_WIDEBAND_SPEECH_ENABLED,
> HCI_EVENT_FILTER_CONFIGURED,
> HCI_PA_SYNC,
> + HCI_SCO_FLOWCTL,
>
> HCI_DUT_MODE,
> HCI_VENDOR_DIAG,
> @@ -1544,6 +1545,11 @@ struct hci_rp_read_tx_power {
> __s8 tx_power;
> } __packed;
>
> +#define HCI_OP_WRITE_SYNC_FLOWCTL 0x0c2f
> +struct hci_cp_write_sync_flowctl {
> + __u8 enable;
> +} __packed;
> +
> #define HCI_OP_READ_PAGE_SCAN_TYPE 0x0c46
> struct hci_rp_read_page_scan_type {
> __u8 status;
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index 2f320eeddfec..cf18cf65fe5e 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -1857,6 +1857,7 @@ void hci_conn_del_sysfs(struct hci_conn *conn);
> #define lmp_hold_capable(dev) ((dev)->features[0][0] & LMP_HOLD)
> #define lmp_sniff_capable(dev) ((dev)->features[0][0] & LMP_SNIFF)
> #define lmp_park_capable(dev) ((dev)->features[0][1] & LMP_PARK)
> +#define lmp_sco_capable(dev) ((dev)->features[0][1] & LMP_SCO)
> #define lmp_inq_rssi_capable(dev) ((dev)->features[0][3] & LMP_RSSI_INQ)
> #define lmp_esco_capable(dev) ((dev)->features[0][3] & LMP_ESCO)
> #define lmp_bredr_capable(dev) (!((dev)->features[0][4] & LMP_NO_BREDR))
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index e7ec12437c8b..63eec8b80ff1 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -3564,11 +3564,25 @@ static void hci_sched_sco(struct hci_dev *hdev)
> BT_DBG("skb %p len %d", skb, skb->len);
> hci_send_frame(hdev, skb);
>
> + hdev->sco_cnt--;
> conn->sent++;
> if (conn->sent == ~0)
> conn->sent = 0;
> }
> }
> +
> + /* Restore sco_cnt if flow control has not been enabled as
> + * HCI_EV_NUM_COMP_PKTS won't be generated.
> + */
> + if (!hci_dev_test_flag(hdev, HCI_SCO_FLOWCTL)) {
> + hdev->sco_cnt = hdev->sco_pkts;
> +
> + /* As flow control is disabled force tx_work to run if there are
> + * still packets left in the queue.
> + */
> + if (conn && !skb_queue_empty(&conn->data_q))
> + queue_work(hdev->workqueue, &hdev->tx_work);
> + }
> }
>
> static void hci_sched_esco(struct hci_dev *hdev)
> @@ -3588,11 +3602,25 @@ static void hci_sched_esco(struct hci_dev *hdev)
> BT_DBG("skb %p len %d", skb, skb->len);
> hci_send_frame(hdev, skb);
>
> + hdev->sco_cnt--;
> conn->sent++;
> if (conn->sent == ~0)
> conn->sent = 0;
> }
> }
> +
> + /* Restore sco_cnt if flow control has not been enabled as
> + * HCI_EV_NUM_COMP_PKTS won't be generated.
> + */
> + if (!hci_dev_test_flag(hdev, HCI_SCO_FLOWCTL)) {
> + hdev->sco_cnt = hdev->sco_pkts;
> +
> + /* As flow control is disabled force tx_work to run if there are
> + * still packets left in the queue.
> + */
> + if (!skb_queue_empty(&conn->data_q))
> + queue_work(hdev->workqueue, &hdev->tx_work);
> + }
> }
>
> static void hci_sched_acl_pkt(struct hci_dev *hdev)
> diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> index c4c2cf51b219..aaa6164fc3e3 100644
> --- a/net/bluetooth/hci_sync.c
> +++ b/net/bluetooth/hci_sync.c
> @@ -3769,6 +3769,27 @@ static int hci_write_ca_timeout_sync(struct hci_dev *hdev)
> sizeof(param), ¶m, HCI_CMD_TIMEOUT);
> }
>
> +/* Enable SCO flow control if supported */
> +static int hci_write_sync_flowctl_sync(struct hci_dev *hdev)
> +{
> + struct hci_cp_write_sync_flowctl cp;
> + int err;
> +
> + /* Check if the controller supports SCO and HCI_OP_WRITE_SYNC_FLOWCTL */
> + if (!lmp_sco_capable(hdev) || !(hdev->commands[10] & BIT(4)))
> + return 0;
> +
> + memset(&cp, 0, sizeof(cp));
> + cp.enable = 0x01;
> +
> + err = __hci_cmd_sync_status(hdev, HCI_OP_WRITE_SYNC_FLOWCTL,
> + sizeof(cp), &cp, HCI_CMD_TIMEOUT);
> + if (!err)
> + hci_dev_set_flag(hdev, HCI_SCO_FLOWCTL);
> +
> + return err;
> +}
> +
> /* BR Controller init stage 2 command sequence */
> static const struct hci_init_stage br_init2[] = {
> /* HCI_OP_READ_BUFFER_SIZE */
> @@ -3787,6 +3808,8 @@ static const struct hci_init_stage br_init2[] = {
> HCI_INIT(hci_clear_event_filter_sync),
> /* HCI_OP_WRITE_CA_TIMEOUT */
> HCI_INIT(hci_write_ca_timeout_sync),
> + /* HCI_OP_WRITE_SYNC_FLOWCTL */
> + HCI_INIT(hci_write_sync_flowctl_sync),
> {}
> };
>
> --
> 2.48.1
Looks like this is working when internally, so I wonder what is going
on if you don't receive NOCP on Intel controllers, that said perhaps
we need some way to detect if NOCP is not being generated, perhaps via
timer, then disable HCI_SCO_FLOWCTL, the issue is this perhaps could
cause hiccups at the start of the stream so perhaps we could do the
opposite and always start without setting HCI_SCO_FLOWCTL and only if
NOCP is generated then set HCI_SCO_FLOWCTL which can then be
persisted, thoughts?
--
Luiz Augusto von Dentz
