Re: [PATCH v1 1/2] Bluetooth: btusb: define HCI packet sizes of USB Alts

It is desirable to define the HCI packet payload sizes of
USB alternate settings so that they can be exposed to user
space.

Reviewed-by: Alain Michaud <redacted>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Joseph Hwang <redacted>
---

 drivers/bluetooth/btusb.c        | 43 ++++++++++++++++++++++++--------
 include/net/bluetooth/hci_core.h |  1 +
 2 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 8d2608ddfd0875..df7cadf6385868 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c

@@ -459,6 +459,22 @@ static const struct dmi_system_id btusb_needs_reset_resume_table[] = {
 #define BTUSB_WAKEUP_DISABLE   14
 #define BTUSB_USE_ALT1_FOR_WBS 15

+/* Per core spec 5, vol 4, part B, table 2.1,
+ * list the hci packet payload sizes for various ALT settings.
+ * This is used to set the packet length for the wideband speech.
+ * If a controller does not probe its usb alt setting, the default
+ * value will be 0. Any clients at upper layers should interpret it
+ * as a default value and set a proper packet length accordingly.
+ *
+ * To calculate the HCI packet payload length:
+ *   for alternate settings 1 - 5:
+ *     hci_packet_size = suggested_max_packet_size * 3 (packets) -
+ *                       3 (HCI header octets)
+ *   for alternate setting 6:
+ *     hci_packet_size = suggested_max_packet_size - 3 (HCI header octets)
+ */
+static const int hci_packet_size_usb_alt[] = { 0, 24, 48, 72, 96, 144, 60 };
+
 struct btusb_data {
        struct hci_dev       *hdev;
        struct usb_device    *udev;

@@ -3958,6 +3974,15 @@ static int btusb_probe(struct usb_interface *intf,
        hdev->notify = btusb_notify;
        hdev->prevent_wake = btusb_prevent_wake;

+       if (id->driver_info & BTUSB_AMP) {
+               /* AMP controllers do not support SCO packets */
+               data->isoc = NULL;
+       } else {
+               /* Interface orders are hardcoded in the specification */
+               data->isoc = usb_ifnum_to_if(data->udev, ifnum_base + 1);
+               data->isoc_ifnum = ifnum_base + 1;
+       }
+
 #ifdef CONFIG_PM
        err = btusb_config_oob_wake(hdev);
        if (err)

@@ -4021,6 +4046,10 @@ static int btusb_probe(struct usb_interface *intf,
                hdev->set_diag = btintel_set_diag;
                hdev->set_bdaddr = btintel_set_bdaddr;
                hdev->cmd_timeout = btusb_intel_cmd_timeout;
+
+               if (btusb_find_altsetting(data, 6))
+                       hdev->sco_pkt_len = hci_packet_size_usb_alt[6];
+
                set_bit(HCI_QUIRK_STRICT_DUPLICATE_FILTER, &hdev->quirks);
                set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
                set_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks);

@@ -4062,15 +4091,6 @@ static int btusb_probe(struct usb_interface *intf,
                btusb_check_needs_reset_resume(intf);
        }

-       if (id->driver_info & BTUSB_AMP) {
-               /* AMP controllers do not support SCO packets */
-               data->isoc = NULL;
-       } else {
-               /* Interface orders are hardcoded in the specification */
-               data->isoc = usb_ifnum_to_if(data->udev, ifnum_base + 1);
-               data->isoc_ifnum = ifnum_base + 1;
-       }
-
        if (IS_ENABLED(CONFIG_BT_HCIBTUSB_RTL) &&
            (id->driver_info & BTUSB_REALTEK)) {
                hdev->setup = btrtl_setup_realtek;

@@ -4082,9 +4102,10 @@ static int btusb_probe(struct usb_interface *intf,
                 * (DEVICE_REMOTE_WAKEUP)
                 */
                set_bit(BTUSB_WAKEUP_DISABLE, &data->flags);
-               if (btusb_find_altsetting(data, 1))
+               if (btusb_find_altsetting(data, 1)) {
                        set_bit(BTUSB_USE_ALT1_FOR_WBS, &data->flags);
-               else
+                       hdev->sco_pkt_len = hci_packet_size_usb_alt[1];
+               } else
                        bt_dev_err(hdev, "Device does not support ALT setting 1");
        }

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 8caac20556b499..0624496328fc09 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h

@@ -417,6 +417,7 @@ struct hci_dev {
        unsigned int    acl_pkts;
        unsigned int    sco_pkts;
        unsigned int    le_pkts;
+       unsigned int    sco_pkt_len;