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Date:   Thu, 10 Sep 2020 14:04:01 +0800
From:   Joseph Hwang <josephsih@...omium.org>
To:     linux-bluetooth@...r.kernel.org, marcel@...tmann.org,
        luiz.dentz@...il.com, pali@...nel.org
Cc:     chromeos-bluetooth-upstreaming@...omium.org, josephsih@...gle.com,
        Joseph Hwang <josephsih@...omium.org>,
        Alain Michaud <alainm@...omium.org>,
        Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v3 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 <alainm@...omium.org>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Signed-off-by: Joseph Hwang <josephsih@...omium.org>
---

Changes in v3:
- Set hdev->sco_mtu to rp->sco_mtu if the latter is smaller.

Changes in v2:
- Used sco_mtu instead of a new sco_pkt_len member in hdev.
- Do not overwrite hdev->sco_mtu in hci_cc_read_buffer_size
  if it has been set in the USB interface.

 drivers/bluetooth/btusb.c | 45 +++++++++++++++++++++++++++++----------
 net/bluetooth/hci_event.c | 14 +++++++++++-
 2 files changed, 47 insertions(+), 12 deletions(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index fe80588c7bd3a8..651d5731a6c6cf 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -459,6 +459,24 @@ 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)
+ *   where suggested_max_packet_size is {9, 17, 25, 33, 49, 63}
+ *   for alt settings 1 - 6.
+ */
+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 +3977,15 @@ 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 +4049,10 @@ 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 +4094,6 @@ 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 +4105,10 @@ 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..1869dc7ebbb5ac 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -730,7 +730,19 @@ 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;
+	/* If the host controller interface is USB, the hdev->sco_mtu is
+	 * set in btusb.c and is not expected to be larger than the max sco
+	 * buffer size returned from the controller in rp->sco_mtu.
+	 */
+	if (hdev->sco_mtu > 0) {
+		if (rp->sco_mtu < hdev->sco_mtu) {
+			BT_ERR("sco mtu %d changed to max sco buffer size %d",
+			       hdev->sco_mtu, rp->sco_mtu);
+			hdev->sco_mtu = rp->sco_mtu;
+		}
+	} else {
+		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);
 
-- 
2.28.0.618.gf4bc123cb7-goog

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