Date:	Mon, 23 Nov 2009 16:21:04 +0100
From:	Oliver Neukum <oliver@...kum.org>
To:	David Brownell <david-b@...bell.net>, stern@...land.harvard.edu,
	"David S. Miller" <davem@...emloft.net>, linux-usb@...r.kernel.org,
	netdev@...r.kernel.org,
	"Torgny Johansson" <torgny.johansson@...csson.com>
Subject: [patch]USB autosuspend for cdc-ether

Hi David,

here's a new, tested version of autosuspend for cdc-ether with
a few glitches fixed. I think it addresses everything you mentioned.
Could you provide some feedback about what's wrong with it or
an acknowledgement?

	Regards
		Oliver

Signed-off-by: Oliver Neukum <oliver@...kum.org>

commit cb0634eee6f96fb24044c961d7dffefed7b6457e
Author: Oliver Neukum <oliver@...kum.org>
Date:   Mon Nov 23 16:04:45 2009 +0100

    usb:cdc-ether:implement power management for online devices
    
    This implements USB autosuspend for cdc-ether devices that
    support remote wakeup while they are online. For reception
    remote wakeup and the last busy functionality of usbcore
    is used.
    Transmission is done with an anchor for deferred transmission
    and the async pm methods of usbcore.
    For devices that don't do remote wakeup power management while
    offline is provided for.

diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
index 21e1ba1..ed55024 100644
--- a/drivers/net/usb/cdc_ether.c
+++ b/drivers/net/usb/cdc_ether.c
@@ -411,6 +411,12 @@ static int cdc_bind(struct usbnet *dev, struct usb_interface *intf)
 	return 0;
 }
 
+static int cdc_manage_power(struct usbnet *dev, int on)
+{
+	dev->intf->needs_remote_wakeup = on;
+	return 0;
+}
+
 static const struct driver_info	cdc_info = {
 	.description =	"CDC Ethernet Device",
 	.flags =	FLAG_ETHER,
@@ -418,6 +424,7 @@ static const struct driver_info	cdc_info = {
 	.bind =		cdc_bind,
 	.unbind =	usbnet_cdc_unbind,
 	.status =	cdc_status,
+	.manage_power =	cdc_manage_power,
 };
 
 /*-------------------------------------------------------------------------*/
@@ -610,6 +617,7 @@ static struct usb_driver cdc_driver = {
 	.disconnect =	usbnet_disconnect,
 	.suspend =	usbnet_suspend,
 	.resume =	usbnet_resume,
+	.supports_autosuspend = 1,
 };
 
 
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index ca5ca5a..4c2d902 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -353,7 +353,8 @@ static void rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
 
 	if (netif_running (dev->net)
 			&& netif_device_present (dev->net)
-			&& !test_bit (EVENT_RX_HALT, &dev->flags)) {
+			&& !test_bit (EVENT_RX_HALT, &dev->flags)
+			&& !test_bit (EVENT_DEV_ASLEEP, &dev->flags)) {
 		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
 		case -EPIPE:
 			usbnet_defer_kevent (dev, EVENT_RX_HALT);
@@ -611,15 +612,39 @@ EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
 /*-------------------------------------------------------------------------*/
 
 // precondition: never called in_interrupt
+static void usbnet_terminate_urbs(struct usbnet *dev)
+{
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK (unlink_wakeup);
+	DECLARE_WAITQUEUE (wait, current);
+	int temp;
+
+	/* ensure there are no more active urbs */
+	add_wait_queue(&unlink_wakeup, &wait);
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	dev->wait = &unlink_wakeup;
+	temp = unlink_urbs(dev, &dev->txq) +
+		unlink_urbs(dev, &dev->rxq);
+
+	/* maybe wait for deletions to finish. */
+	while (!skb_queue_empty(&dev->rxq)
+		&& !skb_queue_empty(&dev->txq)
+		&& !skb_queue_empty(&dev->done)) {
+			schedule_timeout(UNLINK_TIMEOUT_MS);
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			if (netif_msg_ifdown(dev))
+				devdbg(dev, "waited for %d urb completions",
+					temp);
+	}
+	set_current_state(TASK_RUNNING);
+	dev->wait = NULL;
+	remove_wait_queue(&unlink_wakeup, &wait);
+}
 
 int usbnet_stop (struct net_device *net)
 {
 	struct usbnet		*dev = netdev_priv(net);
 	struct driver_info	*info = dev->driver_info;
-	int			temp;
 	int			retval;
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK (unlink_wakeup);
-	DECLARE_WAITQUEUE (wait, current);
 
 	netif_stop_queue (net);
 
@@ -641,25 +666,8 @@ int usbnet_stop (struct net_device *net)
 				info->description);
 	}
 
-	if (!(info->flags & FLAG_AVOID_UNLINK_URBS)) {
-		/* ensure there are no more active urbs */
-		add_wait_queue(&unlink_wakeup, &wait);
-		dev->wait = &unlink_wakeup;
-		temp = unlink_urbs(dev, &dev->txq) +
-			unlink_urbs(dev, &dev->rxq);
-
-		/* maybe wait for deletions to finish. */
-		while (!skb_queue_empty(&dev->rxq)
-				&& !skb_queue_empty(&dev->txq)
-				&& !skb_queue_empty(&dev->done)) {
-			msleep(UNLINK_TIMEOUT_MS);
-			if (netif_msg_ifdown(dev))
-				devdbg(dev, "waited for %d urb completions",
-					temp);
-		}
-		dev->wait = NULL;
-		remove_wait_queue(&unlink_wakeup, &wait);
-	}
+	if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
+		usbnet_terminate_urbs(dev);
 
 	usb_kill_urb(dev->interrupt);
 
@@ -672,7 +680,10 @@ int usbnet_stop (struct net_device *net)
 	dev->flags = 0;
 	del_timer_sync (&dev->delay);
 	tasklet_kill (&dev->bh);
-	usb_autopm_put_interface(dev->intf);
+	if (info->manage_power)
+		info->manage_power(dev, 0);
+	else
+		usb_autopm_put_interface(dev->intf);
 
 	return 0;
 }
@@ -753,6 +764,12 @@ int usbnet_open (struct net_device *net)
 
 	// delay posting reads until we're fully open
 	tasklet_schedule (&dev->bh);
+	if (info->manage_power) {
+		retval = info->manage_power(dev, 1);
+		if (retval < 0)
+			goto done;
+		usb_autopm_put_interface(dev->intf);
+	}
 	return retval;
 done:
 	usb_autopm_put_interface(dev->intf);
@@ -881,11 +898,16 @@ kevent (struct work_struct *work)
 	/* usb_clear_halt() needs a thread context */
 	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
 		unlink_urbs (dev, &dev->txq);
+		status = usb_autopm_get_interface(dev->intf);
+		if (status < 0)
+			goto fail_pipe;
 		status = usb_clear_halt (dev->udev, dev->out);
+		usb_autopm_put_interface(dev->intf);
 		if (status < 0
 				&& status != -EPIPE
 				&& status != -ESHUTDOWN) {
 			if (netif_msg_tx_err (dev))
+fail_pipe:
 				deverr (dev, "can't clear tx halt, status %d",
 					status);
 		} else {
@@ -896,11 +918,16 @@ kevent (struct work_struct *work)
 	}
 	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
 		unlink_urbs (dev, &dev->rxq);
+		status = usb_autopm_get_interface(dev->intf);
+		if (status < 0)
+			goto fail_halt;
 		status = usb_clear_halt (dev->udev, dev->in);
+		usb_autopm_put_interface(dev->intf);
 		if (status < 0
 				&& status != -EPIPE
 				&& status != -ESHUTDOWN) {
 			if (netif_msg_rx_err (dev))
+fail_halt:
 				deverr (dev, "can't clear rx halt, status %d",
 					status);
 		} else {
@@ -919,7 +946,12 @@ kevent (struct work_struct *work)
 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
 		if (urb != NULL) {
 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
+			status = usb_autopm_get_interface(dev->intf);
+			if (status < 0)
+				goto fail_lowmem;
 			rx_submit (dev, urb, GFP_KERNEL);
+			usb_autopm_put_interface(dev->intf);
+fail_lowmem:
 			tasklet_schedule (&dev->bh);
 		}
 	}
@@ -929,7 +961,11 @@ kevent (struct work_struct *work)
 		int			retval = 0;
 
 		clear_bit (EVENT_LINK_RESET, &dev->flags);
+		status = usb_autopm_get_interface(dev->intf);
+		if (status < 0)
+			goto skip_reset;
 		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
+skip_reset:
 			devinfo(dev, "link reset failed (%d) usbnet usb-%s-%s, %s",
 				retval,
 				dev->udev->bus->bus_name, dev->udev->devpath,
@@ -958,7 +994,7 @@ static void tx_complete (struct urb *urb)
 
 		switch (urb->status) {
 		case -EPIPE:
-			usbnet_defer_kevent (dev, EVENT_TX_HALT);
+			usbnet_defer_kevent (dev, EVENT_TX_HALT);		
 			break;
 
 		/* software-driven interface shutdown */
@@ -971,6 +1007,7 @@ static void tx_complete (struct urb *urb)
 		case -EPROTO:
 		case -ETIME:
 		case -EILSEQ:
+			usb_mark_last_busy(dev->udev);
 			if (!timer_pending (&dev->delay)) {
 				mod_timer (&dev->delay,
 					jiffies + THROTTLE_JIFFIES);
@@ -987,6 +1024,7 @@ static void tx_complete (struct urb *urb)
 		}
 	}
 
+	usb_autopm_put_interface_async(dev->intf);
 	urb->dev = NULL;
 	entry->state = tx_done;
 	defer_bh(dev, skb, &dev->txq);
@@ -1058,13 +1096,33 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
 	}
 
 	spin_lock_irqsave (&dev->txq.lock, flags);
+	retval = usb_autopm_get_interface_async(dev->intf);
+	if (retval < 0) {
+		spin_unlock_irqrestore (&dev->txq.lock, flags);
+		goto drop;
+	}
+
+#ifdef CONFIG_PM
+	/* if this triggers the device is still a sleep */
+	if (test_bit(EVENT_DEV_ASLEEP, &dev->flags)) {
+		/* transmission will be done in resume */
+		usb_anchor_urb(urb, &dev->deferred);
+		/* no use to process more packets */
+		netif_stop_queue(net);
+		spin_unlock_irqrestore(&dev->txq.lock, flags);
+		devdbg(dev, "Delaying transmission for resumption");
+		goto deferred;
+	}
+#endif
 
 	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
 	case -EPIPE:
 		netif_stop_queue (net);
 		usbnet_defer_kevent (dev, EVENT_TX_HALT);
+		usb_autopm_put_interface_async(dev->intf);
 		break;
 	default:
+		usb_autopm_put_interface_async(dev->intf);
 		if (netif_msg_tx_err (dev))
 			devdbg (dev, "tx: submit urb err %d", retval);
 		break;
@@ -1088,6 +1146,7 @@ drop:
 		devdbg (dev, "> tx, len %d, type 0x%x",
 			length, skb->protocol);
 	}
+deferred:
 	return NETDEV_TX_OK;
 }
 EXPORT_SYMBOL_GPL(usbnet_start_xmit);
@@ -1255,6 +1314,7 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
 	dev->bh.func = usbnet_bh;
 	dev->bh.data = (unsigned long) dev;
 	INIT_WORK (&dev->kevent, kevent);
+	init_usb_anchor(&dev->deferred);
 	dev->delay.function = usbnet_bh;
 	dev->delay.data = (unsigned long) dev;
 	init_timer (&dev->delay);
@@ -1363,13 +1423,23 @@ int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
 	struct usbnet		*dev = usb_get_intfdata(intf);
 
 	if (!dev->suspend_count++) {
+		spin_lock_irq(&dev->txq.lock);
+		/* don't autosuspend while transmitting */
+		if (dev->txq.qlen && (message.event & PM_EVENT_AUTO)) {
+			spin_unlock_irq(&dev->txq.lock);
+			return -EBUSY;
+		} else {
+			set_bit(EVENT_DEV_ASLEEP, &dev->flags);
+			spin_unlock_irq(&dev->txq.lock);
+		}
 		/*
 		 * accelerate emptying of the rx and queues, to avoid
 		 * having everything error out.
 		 */
 		netif_device_detach (dev->net);
-		(void) unlink_urbs (dev, &dev->rxq);
-		(void) unlink_urbs (dev, &dev->txq);
+		usbnet_terminate_urbs(dev);
+		usb_kill_urb(dev->interrupt);
+		
 		/*
 		 * reattach so runtime management can use and
 		 * wake the device
@@ -1383,10 +1453,34 @@ EXPORT_SYMBOL_GPL(usbnet_suspend);
 int usbnet_resume (struct usb_interface *intf)
 {
 	struct usbnet		*dev = usb_get_intfdata(intf);
+	struct sk_buff          *skb;
+	struct urb              *res;
+	int                     retval;
+	
+	if (!--dev->suspend_count) {
+		spin_lock_irq(&dev->txq.lock);
+		while ((res = usb_get_from_anchor(&dev->deferred))) {
+
+			printk(KERN_INFO"Called %s with delayed data\n", __func__);
+			skb = (struct sk_buff *)res->context;
+			retval = usb_submit_urb(res, GFP_ATOMIC);
+			if (retval < 0) {
+				dev_kfree_skb_any(skb);
+				usb_free_urb(res);
+				usb_autopm_put_interface_async(dev->intf);
+			} else {
+				dev->net->trans_start = jiffies;
+				__skb_queue_tail (&dev->txq, skb);
+			}
+		}
 
-	if (!--dev->suspend_count)
+		smp_mb();
+		clear_bit(EVENT_DEV_ASLEEP, &dev->flags);
+		spin_unlock_irq(&dev->txq.lock);
+		if (!(dev->txq.qlen >= TX_QLEN(dev)))
+			netif_start_queue(dev->net);
 		tasklet_schedule (&dev->bh);
-
+	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(usbnet_resume);
diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
index f814730..e75ba0e 100644
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -55,6 +55,7 @@ struct usbnet {
 	struct sk_buff_head	done;
 	struct sk_buff_head	rxq_pause;
 	struct urb		*interrupt;
+	struct usb_anchor	deferred;
 	struct tasklet_struct	bh;
 
 	struct work_struct	kevent;
@@ -65,6 +66,8 @@ struct usbnet {
 #		define EVENT_STS_SPLIT	3
 #		define EVENT_LINK_RESET	4
 #		define EVENT_RX_PAUSED	5
+#             define EVENT_DEV_WAKING 6 
+#             define EVENT_DEV_ASLEEP 7 
 };
 
 static inline struct usb_driver *driver_of(struct usb_interface *intf)
@@ -107,6 +110,9 @@ struct driver_info {
 	/* see if peer is connected ... can sleep */
 	int	(*check_connect)(struct usbnet *);
 
+	/* (dis)activate runtime power management */
+	int	(*manage_power)(struct usbnet *, int);
+
 	/* for status polling */
 	void	(*status)(struct usbnet *, struct urb *);
 
--
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