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SCO audio sync with commands

PATCH New Hunyue Yau 1 participant 1 message Nov 1, 2007

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Hunyue Yau

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PATCH 1/1 SCO audio sync with commands

Hi,

Following up for my posting a few days ago, this patch works around the synchronization problem where SCO data is queued up in the hci_usb driver, and the socket is closed. Since there are multiple queues corresponding to the different USB pipes, the DISCONNECT command gets to the hardware before the data finishes.

This is likely not to be a good long term fix but it works. Comments on a better long term fix? Patch is against 2.6.21 + sco flowcontrol v4.2 patch. Also applies to 2.6.23.1.

-- Hunyue
---------------------------------------------------------------------------------------------------------

Signed-off-by Hunyue Yau <[email protected]>

Description:
Certain bluetooth adapter drivers such as hci_usb provide different queues for command, data, and SCO data packets. This introduces a situation where the one relative timing of commands to data can be lost. An example is SCO data can be queued in the SCO queue waiting to be sent and a DISCONNECT command is sent from the higher level HCI stack. With the multiple queues, the DISCONNECT command can be sent to the device before the SCO data queue is drained. As a result, the hardware can confused.

This change adds an API to the hardware drivers to query the amount of pending data in its queue SCO data queue. This queue was specificly choosen due to its fix rate draining characteristic. Prior to sending a disconnect, if the current device implements this new API, it is queried. The connection is not disconnected until the queue completely drains.

drivers/bluetooth/hci_usb.c +11 -0
Index: linux-2.6.21/drivers/bluetooth/hci_usb.c
===================================================================
@@ -842,6 +842,14 @@ static void hci_usb_notify(struct hci_de
 	BT_DBG("%s evt %d", hdev->name, evt);
 }
 
+#ifdef CONFIG_BT_HCIUSB_SCO
+static int hci_usb_sco_q_pend(struct hci_dev *hdev)
+{
+	struct hci_usb *husb = (struct hci_usb *) hdev->driver_data;
+	return atomic_read(__pending_tx(husb, HCI_SCODATA_PKT));
+}
+#endif
+
 static int hci_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 {
 	struct usb_device *udev = interface_to_usbdev(intf);

@@ -1004,6 +1012,9 @@ static int hci_usb_probe(struct usb_inte
 	hdev->send     = hci_usb_send_frame;
 	hdev->destruct = hci_usb_destruct;
 	hdev->notify   = hci_usb_notify;
+#ifdef CONFIG_BT_HCIUSB_SCO
+	hdev->sco_queue_pend	= hci_usb_sco_q_pend;
+#endif
 
 	hdev->owner = THIS_MODULE;
include/net/bluetooth/hci_core.h +1 -0
Index: linux-2.6.21/include/net/bluetooth/hci_core.h
===================================================================
@@ -141,6 +141,7 @@ struct hci_dev {
 	void (*destruct)(struct hci_dev *hdev);
 	void (*notify)(struct hci_dev *hdev, unsigned int evt);
 	int (*ioctl)(struct hci_dev *hdev, unsigned int cmd, unsigned long arg);
+	int (*sco_queue_pend)(struct hci_dev *hdev);
 };
 
 struct hci_conn {
net/bluetooth/hci_conn.c +12 -0
Index: linux-2.6.21/net/bluetooth/hci_conn.c
===================================================================
@@ -133,6 +133,8 @@ static void hci_conn_timeout(unsigned lo
 {
 	struct hci_conn *conn = (void *) arg;
 	struct hci_dev *hdev = conn->hdev;
+	int	q_len = 0;
+	unsigned long timeo;
 
 	BT_DBG("conn %p state %d", conn, conn->state);
 

@@ -146,6 +148,16 @@ static void hci_conn_timeout(unsigned lo
 		hci_acl_connect_cancel(conn);
 		break;
 	case BT_CONNECTED:
+		if (conn->type == SCO_LINK) {
+			if (hdev->sco_queue_pend) {
+				q_len = (hdev->sco_queue_pend)(hdev);
+				if (q_len > 0) {
+					timeo = msecs_to_jiffies(1000);
+					mod_timer(&conn->disc_timer, jiffies + timeo);
+					break;
+				}
+			}
+		}
 		hci_acl_disconn(conn, 0x13);
 		break;
 	default:

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