[Bluez-devel] Handling simultaneous SCO connections: Does BlueZ have multiple SCO buffers?

[Bluez-devel] Handling simultaneous SCO connections: Does BlueZ have multiple SCO buffers?

[George Hansel]

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I'm working on a project which is trying to handle multiple SCO
connections and data transfer (from cell phones) simultaneously, whether
that involves using multiple Bluetooth adapters on a single computer
(one SCO connection per adapter) or multiple connections per adapter (up
to the maximum of 3).

I have a process which handles the initial RFCOMM setup, the AT commands
involved in having the computer pretend to be a Hands-Free Device, and
accepts an SCO connection once the phone initiates. It's written in
Python using the PyBlueZ module. Multiple processes are launched in
order to handle multiple connections, and I've so far been able to
establish multiple RFCOMM connections on a single and on multiple
adapters.

The problem arises when I try to start multiple SCO connections (by
pressing buttons on the cell phone, so as to send DTMF tones over the
connection). I am not able to establish multiple simultaneous SCO
connections, and not only that, but the SCO data is directed to a
different process every time the SCO connection resets (due to 3 seconds
of silence - this is a feature of the Hands-Free Profile). This makes it
seem as though there is only one SCO buffer somewhere in the stack, and
any waiting process just reads from it, assuming that it's the proper
data. 

My question: Is it true that BlueZ has only one buffer for SCO data? If
this is true, where in the BlueZ stack is this single implementation (in
the kernel drivers? in the bluez-libs? in the bluez-utils?)? I'd have no
reservations about trying to implement a second (or third, as the
protocol truly demands) one. Lastly, if this is not a BlueZ problem at
all, but rather a hardware or PyBlueZ issue, just let me know.

Thanks for any consideration,
George

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Re: [Bluez-devel] Handling simultaneous SCO connections: Does BlueZ have multiple SCO buffers?

[Brad Midgley]

George

bluetooth adapters that are connected by usb need to have a kernel mod
to allow the alternate setting to be changed dynamically. There's an
experimental patch out there:

http://article.gmane.org/gmane.linux.bluez.devel/11999

the patch also assumes you have the flowcontrol patch applied first:

http://bluetooth-alsa.cvs.sourceforge.net/bluetooth-alsa/plugz/patches/sco-flowcontrol-v4.2.diff?view=log

Brad

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Re: [Bluez-devel] Handling simultaneous SCO connections: Does BlueZhave multiple SCO buffers?

[Niels v/d Spek]

Brad Midgley wrote:
> George
>
> bluetooth adapters that are connected by usb need to have a kernel mod
> to allow the alternate setting to be changed dynamically. There's an
> experimental patch out there:
>
> http://article.gmane.org/gmane.linux.bluez.devel/11999
>
> the patch also assumes you have the flowcontrol patch applied first:
>
> http://bluetooth-alsa.cvs.sourceforge.net/bluetooth-alsa/plugz/patches/sco-flowcontrol-v4.2.diff?view=log
>
Brad,

I'm using Ubuntu 7.4 and like to know of this patches are there also needed?

thanks anyway

Niels
> Brad
>
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Re: [Bluez-devel] Handling simultaneous SCO connections: Does BlueZhave multiple SCO buffers?

[George Hansel]

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On Thu, 2007-07-12 at 06:58 +0200, Niels v/d Spek wrote:

> Brad Midgley wrote:
> > George
> >
> > bluetooth adapters that are connected by usb need to have a kernel mod
> > to allow the alternate setting to be changed dynamically. There's an
> > experimental patch out there:
> >
> > http://article.gmane.org/gmane.linux.bluez.devel/11999
> >
> > the patch also assumes you have the flowcontrol patch applied first:
> >
> > http://bluetooth-alsa.cvs.sourceforge.net/bluetooth-alsa/plugz/patches/sco-flowcontrol-v4.2.diff?view=log
> >
> Brad,
> 
> I'm using Ubuntu 7.4 and like to know of this patches are there also needed?
> 
> thanks anyway
> 
> Niels
> > Brad
> >
> > -------------------------------------------------------------------------


Neils,

I am also using Ubuntu 7.04 (latest patches, etc). As it turned out, I
created a workaround for my problem, not using the patches. Depending on
your application, you will need them as well. The Bluetooth stack is
developed independently, but is incorporated into the Linux kernel, and
so should be quite uniform throughout different distributions.

George

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Re: [Bluez-devel] Handling simultaneous SCO connections: Does BlueZhave multiple SCO buffers?

[Alok]

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On Thu, 2007-07-12 at 04:01 -0400, George Hansel wrote:
> On Thu, 2007-07-12 at 06:58 +0200, Niels v/d Spek wrote: 
> > Brad Midgley wrote:
> > > George
> > >
> > > bluetooth adapters that are connected by usb need to have a kernel mod
> > > to allow the alternate setting to be changed dynamically. There's an
> > > experimental patch out there:
> > >
> > > http://article.gmane.org/gmane.linux.bluez.devel/11999
> > >
> > > the patch also assumes you have the flowcontrol patch applied first:
> > >
> > > http://bluetooth-alsa.cvs.sourceforge.net/bluetooth-alsa/plugz/patches/sco-flowcontrol-v4.2.diff?view=log
> > >
> > Brad,
> > 
> > I'm using Ubuntu 7.4 and like to know of this patches are there also needed?
> > 
> > thanks anyway
> > 
> > Niels
> > > Brad
> > >
> > > -------------------------------------------------------------------------
> 
> Neils,
> 
> I am also using Ubuntu 7.04 (latest patches, etc). As it turned out, I
> created a workaround for my problem, not using the patches. Depending
> on your application, you will need them as well. The Bluetooth stack
> is developed independently, but is incorporated into the Linux kernel,
> and so should be quite uniform throughout different distributions.
> 
> George 

Hi, 

If you want to use  multiple SCO connections (and your adapter is
connected through USB )you need the alternate setting patch along with
the sco-flowcontrol patch.

Brad, There are some changes in that patch , I am attaching the latest
one. 
There can be some issues which i might have missed, will test it out and
send a final patch soon. 



Thanks to Whoopie for testing the new patch . 
 

Thanks, 
Alok Barsode.
  

[-- Attachment #2: alternate-setting.patch --]
[-- Type: text/x-patch, Size: 5978 bytes --]

diff --git a/drivers/bluetooth/hci_usb.c b/drivers/bluetooth/hci_usb.c
index 406af57..03b362e 100644
--- a/drivers/bluetooth/hci_usb.c
+++ b/drivers/bluetooth/hci_usb.c
@@ -837,11 +837,112 @@ static void hci_usb_destruct(struct hci_dev *hdev)
 	kfree(husb);
 }
 
+#ifdef CONFIG_BT_HCIUSB_SCO
 static void hci_usb_notify(struct hci_dev *hdev, unsigned int evt)
 {
+	struct hci_usb *husb = (struct hci_usb *) hdev->driver_data;
+	unsigned long flags;
+	int new_alts;
+
 	BT_DBG("%s evt %d", hdev->name, evt);
+	new_alts = hdev->conn_hash.sco_num;
+	
+	if(hdev->voice_setting & 0x0020){
+		new_alts *= 2;
+		if(new_alts > 5)
+			new_alts = 5;
+	}
+		
+	write_lock_irqsave(&husb->completion_lock, flags);
+
+	if(new_alts != husb->curr_isoc_alts){
+		husb->new_isoc_alts = new_alts;
+		schedule_work(&husb->work);
+	}
+
+	write_unlock_irqrestore(&husb->completion_lock, flags); 
+    
 }
 
+static void set_isoc_alternate(struct work_struct *work)
+{
+	struct hci_usb *husb = container_of(work, struct hci_usb, work);
+	struct _urb *_urb, *_tmp;
+	struct _urb_queue *q = &husb->pending_q[isoc];
+	/*This list holds the already submitted URBs */
+	struct list_head inprocess;
+	unsigned long flags;
+	/*Holds the number of URBs we need to skip(which are submitted) */
+	atomic_t temp;
+	int isoc_ifnum=1,e;
+
+	struct usb_interface *isocIface;
+	struct usb_host_endpoint *ep;
+	struct usb_host_interface *uif;
+	struct usb_host_endpoint *out = NULL;
+	struct usb_host_endpoint *in = NULL;
+
+	INIT_LIST_HEAD(&inprocess);
+	temp = husb->pending_tx[isoc];
+	
+	while ((_urb = _urb_dequeue(q))) {
+		/*Dequeue all the submitted URBs and put them in the temporary list */
+		if (!atomic_dec_and_test(&temp)) {
+			_urb->queue = q;
+			list_add(&_urb->list, &inprocess);
+		} else {
+			/*Unlink all the rest of URBs and put them into the completed queue. */
+			_urb_unlink(_urb);
+			_urb_queue_tail(__completed_q(husb, HCI_SCODATA_PKT),
+					_urb);
+		}
+	}
+	/*merge the inprocess queue with the pending queue */
+	spin_lock_irqsave(&q->lock, flags);
+	list_for_each_entry_safe(_urb, _tmp, &inprocess, list) {
+		list_move_tail(&_urb->list, &q->head);
+	}
+	spin_unlock_irqrestore(&q->lock, flags);
+	clear_bit(HCI_USB_TX_WAKEUP, &husb->state);
+	isocIface = usb_ifnum_to_if(husb->udev, isoc_ifnum); 
+	
+	/* Set the setting and the in/out endpoints */
+	if (isocIface) {
+		uif = &isocIface->altsetting[husb->new_isoc_alts];
+		for (e = 0; e < uif->desc.bNumEndpoints; e++) {
+			ep = &uif->endpoint[e];
+			switch (ep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) {
+			case USB_ENDPOINT_XFER_ISOC:
+				if (ep->desc.bEndpointAddress & USB_DIR_IN)
+					in = ep;
+				else
+					out = ep;
+				break;
+			}
+		}
+		if (!in || !out)
+			BT_DBG("Isoc endpoints not found");
+		else {
+			BT_DBG("isoc ifnum %d alts %d", isoc_ifnum, husb->new_isoc_alts);
+
+			if (usb_set_interface(husb->udev, isoc_ifnum, husb->new_isoc_alts)) {
+				BT_ERR("Can't set isoc interface settings");
+				husb->isoc_iface = isocIface;
+				usb_driver_release_interface(&hci_usb_driver,husb->isoc_iface);
+				husb->isoc_iface = NULL;
+			} else {
+				husb->isoc_iface = isocIface;
+				husb->isoc_in_ep = in;
+				husb->isoc_out_ep = out;
+				husb->curr_isoc_alts = husb->new_isoc_alts;
+			}
+		}
+	}
+
+	set_bit(HCI_USB_TX_WAKEUP, &husb->state);
+}
+#endif
+
 static int hci_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 {
 	struct usb_device *udev = interface_to_usbdev(intf);
@@ -853,7 +954,7 @@ static int hci_usb_probe(struct usb_interface *intf, const struct usb_device_id
 	struct usb_interface *isoc_iface;
 	struct hci_usb *husb;
 	struct hci_dev *hdev;
-	int i, e, size, isoc_ifnum, isoc_alts;
+	int i, e, size, isoc_ifnum;
 
 	BT_DBG("udev %p intf %p", udev, intf);
 
@@ -922,7 +1023,7 @@ static int hci_usb_probe(struct usb_interface *intf, const struct usb_device_id
 	/* Find isochronous endpoints that we can use */
 	size = 0; 
 	isoc_iface = NULL;
-	isoc_alts  = 0;
+	husb->curr_isoc_alts  = 0;
 	isoc_ifnum = 1;
 
 #ifdef CONFIG_BT_HCIUSB_SCO
@@ -946,7 +1047,7 @@ static int hci_usb_probe(struct usb_interface *intf, const struct usb_device_id
 						break;
 					size = le16_to_cpu(ep->desc.wMaxPacketSize);
 
-					isoc_alts = uif->desc.bAlternateSetting;
+					husb->curr_isoc_alts = uif->desc.bAlternateSetting;
 
 					if (ep->desc.bEndpointAddress & USB_DIR_IN)
 						isoc_in_ep  = ep;
@@ -960,10 +1061,10 @@ static int hci_usb_probe(struct usb_interface *intf, const struct usb_device_id
 		if (!isoc_in_ep || !isoc_out_ep)
 			BT_DBG("Isoc endpoints not found");
 		else {
-			BT_DBG("isoc ifnum %d alts %d", isoc_ifnum, isoc_alts);
+			BT_DBG("isoc ifnum %d alts %d", isoc_ifnum, husb->curr_isoc_alts);
 			if (usb_driver_claim_interface(&hci_usb_driver, isoc_iface, husb) != 0)
 				BT_ERR("Can't claim isoc interface");
-			else if (usb_set_interface(udev, isoc_ifnum, isoc_alts)) {
+			else if (usb_set_interface(udev, isoc_ifnum, husb->curr_isoc_alts)) {
 				BT_ERR("Can't set isoc interface settings");
 				husb->isoc_iface = isoc_iface;
 				usb_driver_release_interface(&hci_usb_driver, isoc_iface);
@@ -975,6 +1076,7 @@ static int hci_usb_probe(struct usb_interface *intf, const struct usb_device_id
 			}
 		}
 	}
+	INIT_WORK(&husb->work,set_isoc_alternate);
 #endif
 
 	rwlock_init(&husb->completion_lock);
diff --git a/drivers/bluetooth/hci_usb.h b/drivers/bluetooth/hci_usb.h
index 963fc55..c9fbf0e 100644
--- a/drivers/bluetooth/hci_usb.h
+++ b/drivers/bluetooth/hci_usb.h
@@ -108,11 +108,14 @@ struct hci_usb {
 	struct usb_host_endpoint	*bulk_in_ep;
 	struct usb_host_endpoint	*bulk_out_ep;
 	struct usb_host_endpoint	*intr_in_ep;
-
+#ifdef CONFIG_BT_HCIUSB_SCO
 	struct usb_interface		*isoc_iface;
 	struct usb_host_endpoint	*isoc_out_ep;
 	struct usb_host_endpoint	*isoc_in_ep;
-
+	struct work_struct           work;
+	int curr_isoc_alts;
+	int new_isoc_alts;
+#endif
 	__u8			ctrl_req;
 
 	struct sk_buff_head	transmit_q[4];

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