Hi Hsin-chen, On Thu, Feb 27, 2025 at 12:14 PM Hsin-chen Chuang <chharry@xxxxxxxxxx> wrote: > > From: Hsin-chen Chuang <chharry@xxxxxxxxxxxx> > > Automatically configure the altsetting for HCI_USER_CHANNEL when a SCO > is connected. > > The motivation is to enable the HCI_USER_CHANNEL user to send out SCO > data through USB Bluetooth chips, which is mainly used for bidirectional > audio transfer (voice call). This was not capable because: > > - Per Bluetooth Core Spec v5, Vol 4, Part B, 2.1, the corresponding > alternate setting should be set based on the air mode in order to > transfer SCO data, but > - The Linux Bluetooth HCI_USER_CHANNEL exposes the Bluetooth Host > Controller Interface to the user space, which is something above the > USB layer. The user space is not able to configure the USB alt while > keeping the channel open. > > This patch intercepts the HCI_EV_SYNC_CONN_COMPLETE packets in btusb, > extracts the air mode, and configures the alt setting in btusb. > > This patch is tested on ChromeOS devices. The USB Bluetooth models > (CVSD, TRANS alt3 and alt6) could work without a customized kernel. > > Fixes: b16b327edb4d ("Bluetooth: btusb: add sysfs attribute to control USB alt setting") > Signed-off-by: Hsin-chen Chuang <chharry@xxxxxxxxxxxx> > --- > > Changes in v3: > - Remove module parameter > - Set Kconfig to default y if CHROME_PLATFORMS > > Changes in v2: > - Give up tracking the SCO handles. Only configure the altsetting when > SCO connected. > - Put the change behind Kconfig/module parameter > > drivers/bluetooth/Kconfig | 11 ++++++++++ > drivers/bluetooth/btusb.c | 43 +++++++++++++++++++++++++++++++++++++++ > 2 files changed, 54 insertions(+) > > diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig > index 4ab32abf0f48..cdf7a5caa5c8 100644 > --- a/drivers/bluetooth/Kconfig > +++ b/drivers/bluetooth/Kconfig > @@ -56,6 +56,17 @@ config BT_HCIBTUSB_POLL_SYNC > Say Y here to enable USB poll_sync for Bluetooth USB devices by > default. > > +config BT_HCIBTUSB_AUTO_SET_ISOC_ALT > + bool "Auto set isoc_altsetting for HCI_USER_CHANNEL when SCO connected" > + depends on BT_HCIBTUSB > + default y if CHROME_PLATFORMS > + help > + Say Y here to enable auto set isoc_altsetting for HCI_USER_CHANNEL > + when SCO connected > + > + When enabled, btusb intercepts the HCI_EV_SYNC_CONN_COMPLETE packets > + and configures isoc_altsetting automatically for HCI_USER_CHANNEL. > + > config BT_HCIBTUSB_BCM > bool "Broadcom protocol support" > depends on BT_HCIBTUSB > diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c > index de3fa725d210..2642d2ca885f 100644 > --- a/drivers/bluetooth/btusb.c > +++ b/drivers/bluetooth/btusb.c > @@ -34,6 +34,8 @@ static bool force_scofix; > static bool enable_autosuspend = IS_ENABLED(CONFIG_BT_HCIBTUSB_AUTOSUSPEND); > static bool enable_poll_sync = IS_ENABLED(CONFIG_BT_HCIBTUSB_POLL_SYNC); > static bool reset = true; > +static bool auto_set_isoc_alt = > + IS_ENABLED(CONFIG_BT_HCIBTUSB_AUTO_SET_ISOC_ALT); > > static struct usb_driver btusb_driver; > > @@ -1113,6 +1115,42 @@ static inline void btusb_free_frags(struct btusb_data *data) > spin_unlock_irqrestore(&data->rxlock, flags); > } > > +static void btusb_sco_connected(struct btusb_data *data, struct sk_buff *skb) > +{ > + struct hci_event_hdr *hdr = (void *) skb->data; > + struct hci_ev_sync_conn_complete *ev = > + (void *) skb->data + sizeof(*hdr); > + struct hci_dev *hdev = data->hdev; > + unsigned int notify_air_mode; > + > + if (hci_skb_pkt_type(skb) != HCI_EVENT_PKT) > + return; > + > + if (skb->len < sizeof(*hdr) || hdr->evt != HCI_EV_SYNC_CONN_COMPLETE) > + return; > + > + if (skb->len != sizeof(*hdr) + sizeof(*ev) || ev->status) > + return; > + > + switch (ev->air_mode) { > + case BT_CODEC_CVSD: > + notify_air_mode = HCI_NOTIFY_ENABLE_SCO_CVSD; > + break; > + > + case BT_CODEC_TRANSPARENT: > + notify_air_mode = HCI_NOTIFY_ENABLE_SCO_TRANSP; > + break; > + > + default: > + return; > + } > + > + bt_dev_info(hdev, "enabling SCO with air mode %u", ev->air_mode); > + data->sco_num = 1; > + data->air_mode = notify_air_mode; > + schedule_work(&data->work); > +} > + > static int btusb_recv_event(struct btusb_data *data, struct sk_buff *skb) > { > if (data->intr_interval) { > @@ -1120,6 +1158,11 @@ static int btusb_recv_event(struct btusb_data *data, struct sk_buff *skb) > schedule_delayed_work(&data->rx_work, 0); > } > > + /* Configure altsetting for HCI_USER_CHANNEL on SCO connected */ > + if (auto_set_isoc_alt && > + hci_dev_test_flag(data->hdev, HCI_USER_CHANNEL)) > + btusb_sco_connected(data, skb); > + > return data->recv_event(data->hdev, skb); > } > > -- > 2.48.1.658.g4767266eb4-goog This has been merged, I did some minor rewording here and there but the logic remains the same, now we can problem revert b16b327edb4d ("Bluetooth: btusb: add sysfs attribute to control USB alt setting")? -- Luiz Augusto von Dentz