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 <ala...@chromium.org>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpan...@chromium.org>
Signed-off-by: Joseph Hwang <joseph...@chromium.org>
---

Changes in v2:
- 1/2: Used sco_mtu instead of a new sco_pkt_len member in hdev.
- 1/2: Do not overwrite hdev->sco_mtu in hci_cc_read_buffer_size
  if it has been set in the USB interface.
- 2/2: Used BT_SNDMTU/BT_RCVMTU instead of creating a new opt name.
- 2/2: Used the existing conn->mtu instead of creating a new member
       in struct sco_pinfo.
- 2/2: Noted that the old SCO_OPTIONS in sco_sock_getsockopt_old()
       would just work as it uses sco_pi(sk)->conn->mtu.

 drivers/bluetooth/btusb.c | 43 +++++++++++++++++++++++++++++----------
 net/bluetooth/hci_event.c |  7 ++++++-
 2 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index fe80588c7bd3a8..a710233382afff 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;
@@ -3959,6 +3975,15 @@ 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)
@@ -4022,6 +4047,10 @@ 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_mtu = 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);
@@ -4063,15 +4092,6 @@ 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;
@@ -4083,9 +4103,10 @@ 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_mtu = hci_packet_size_usb_alt[1];
+               } else
                        bt_dev_err(hdev, "Device does not support ALT setting 
1");
        }
 
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 33d8458fdd4adc..b3e9247fdbcfa1 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -730,7 +730,12 @@ static void hci_cc_read_buffer_size(struct hci_dev *hdev, 
struct sk_buff *skb)
                return;
 
        hdev->acl_mtu  = __le16_to_cpu(rp->acl_mtu);
-       hdev->sco_mtu  = rp->sco_mtu;
+       /* Set sco_mtu only when not yet.
+        * The sco_mtu would be set in btusb.c
+        * if the host controller interface is USB.
+        */
+       if (hdev->sco_mtu == 0)
+               hdev->sco_mtu  = rp->sco_mtu;
        hdev->acl_pkts = __le16_to_cpu(rp->acl_max_pkt);
        hdev->sco_pkts = __le16_to_cpu(rp->sco_max_pkt);
 
-- 
2.28.0.526.ge36021eeef-goog

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