Commit 716fb91d authored by Weinn Jheng's avatar Weinn Jheng Committed by Felipe Balbi
Browse files

usb: gadget: u_ether: move hardware transmit to RX NAPI 



In order to reduce the interrupt times in the embedded system,
a receiving workqueue is introduced.
This modification also enhanced the overall throughput as the
benefits of reducing interrupt occurrence.

This work was derived from previous work:
u_ether: move hardware transmit to RX workqueue.
Which should be base on codeaurora's work.

However, the benchmark on my platform shows the throughput
with workqueue is slightly better than NAPI.

Signed-off-by: default avatarWeinn Jheng <clanlab.proj@gmail.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Manu Gautam <mgautam@codeaurora.org>
Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
parent 3f89204b

drivers/usb/gadget/u_ether.c

+66 −35
Original line number Diff line number Diff line
@@ -48,6 +48,8 @@ 


#define UETH__VERSION	"29-May-2008"



#define GETHER_NAPI_WEIGHT	32



struct eth_dev {

	/* lock is held while accessing port_usb

	 */
@@ -72,6 +74,7 @@ struct eth_dev { 
						struct sk_buff_head *list);



	struct work_struct	work;

	struct napi_struct	rx_napi;



	unsigned long		todo;

#define	WORK_RX_MEMORY		0
@@ -253,18 +256,16 @@ enomem: 
		DBG(dev, "rx submit --> %d\n", retval);

		if (skb)

			dev_kfree_skb_any(skb);

		spin_lock_irqsave(&dev->req_lock, flags);

		list_add(&req->list, &dev->rx_reqs);

		spin_unlock_irqrestore(&dev->req_lock, flags);

	}

	return retval;

}



static void rx_complete(struct usb_ep *ep, struct usb_request *req)

{

	struct sk_buff	*skb = req->context, *skb2;

	struct sk_buff	*skb = req->context;

	struct eth_dev	*dev = ep->driver_data;

	int		status = req->status;

	bool		rx_queue = 0;



	switch (status) {
@@ -288,30 +289,8 @@ static void rx_complete(struct usb_ep *ep, struct usb_request *req) 
		} else {

			skb_queue_tail(&dev->rx_frames, skb);

		}

		skb = NULL;



		skb2 = skb_dequeue(&dev->rx_frames);

		while (skb2) {

			if (status < 0

					|| ETH_HLEN > skb2->len

					|| skb2->len > VLAN_ETH_FRAME_LEN) {

				dev->net->stats.rx_errors++;

				dev->net->stats.rx_length_errors++;

				DBG(dev, "rx length %d\n", skb2->len);

				dev_kfree_skb_any(skb2);

				goto next_frame;

			}

			skb2->protocol = eth_type_trans(skb2, dev->net);

			dev->net->stats.rx_packets++;

			dev->net->stats.rx_bytes += skb2->len;



			/* no buffer copies needed, unless hardware can't

			 * use skb buffers.

			 */

			status = netif_rx(skb2);

next_frame:

			skb2 = skb_dequeue(&dev->rx_frames);

		}

		if (!status)

			rx_queue = 1;

		break;



	/* software-driven interface shutdown */
@@ -334,22 +313,20 @@ quiesce: 
		/* FALLTHROUGH */



	default:

		rx_queue = 1;

		dev_kfree_skb_any(skb);

		dev->net->stats.rx_errors++;

		DBG(dev, "rx status %d\n", status);

		break;

	}



	if (skb)

		dev_kfree_skb_any(skb);

	if (!netif_running(dev->net)) {

clean:

		spin_lock(&dev->req_lock);

		list_add(&req->list, &dev->rx_reqs);

		spin_unlock(&dev->req_lock);

		req = NULL;

	}

	if (req)

		rx_submit(dev, req, GFP_ATOMIC);



	if (rx_queue && likely(napi_schedule_prep(&dev->rx_napi)))

		__napi_schedule(&dev->rx_napi);

}



static int prealloc(struct list_head *list, struct usb_ep *ep, unsigned n)
@@ -414,16 +391,24 @@ static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags) 
{

	struct usb_request	*req;

	unsigned long		flags;

	int			rx_counts = 0;



	/* fill unused rxq slots with some skb */

	spin_lock_irqsave(&dev->req_lock, flags);

	while (!list_empty(&dev->rx_reqs)) {



		if (++rx_counts > qlen(dev->gadget, dev->qmult))

			break;



		req = container_of(dev->rx_reqs.next,

				struct usb_request, list);

		list_del_init(&req->list);

		spin_unlock_irqrestore(&dev->req_lock, flags);



		if (rx_submit(dev, req, gfp_flags) < 0) {

			spin_lock_irqsave(&dev->req_lock, flags);

			list_add(&req->list, &dev->rx_reqs);

			spin_unlock_irqrestore(&dev->req_lock, flags);

			defer_kevent(dev, WORK_RX_MEMORY);

			return;

		}
@@ -433,6 +418,41 @@ static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags) 
	spin_unlock_irqrestore(&dev->req_lock, flags);

}



static int gether_poll(struct napi_struct *napi, int budget)

{

	struct eth_dev  *dev = container_of(napi, struct eth_dev, rx_napi);

	struct sk_buff	*skb;

	unsigned int	work_done = 0;

	int		status = 0;



	while ((skb = skb_dequeue(&dev->rx_frames))) {

		if (status < 0

				|| ETH_HLEN > skb->len

				|| skb->len > VLAN_ETH_FRAME_LEN) {

			dev->net->stats.rx_errors++;

			dev->net->stats.rx_length_errors++;

			DBG(dev, "rx length %d\n", skb->len);

			dev_kfree_skb_any(skb);

			continue;

		}

		skb->protocol = eth_type_trans(skb, dev->net);

		dev->net->stats.rx_packets++;

		dev->net->stats.rx_bytes += skb->len;



		status = netif_rx_ni(skb);

	}



	if (netif_running(dev->net)) {

		rx_fill(dev, GFP_KERNEL);

		work_done++;

	}



	if (work_done < budget)

		napi_complete(&dev->rx_napi);



	return work_done;

}



static void eth_work(struct work_struct *work)

{

	struct eth_dev	*dev = container_of(work, struct eth_dev, work);
@@ -625,6 +645,7 @@ static void eth_start(struct eth_dev *dev, gfp_t gfp_flags) 
	/* and open the tx floodgates */

	atomic_set(&dev->tx_qlen, 0);

	netif_wake_queue(dev->net);

	napi_enable(&dev->rx_napi);

}



static int eth_open(struct net_device *net)
@@ -651,6 +672,7 @@ static int eth_stop(struct net_device *net) 
	unsigned long	flags;



	VDBG(dev, "%s\n", __func__);

	napi_disable(&dev->rx_napi);

	netif_stop_queue(net);



	DBG(dev, "stop stats: rx/tx %ld/%ld, errs %ld/%ld\n",
@@ -768,6 +790,7 @@ struct eth_dev *gether_setup_name(struct usb_gadget *g, 
		return ERR_PTR(-ENOMEM);



	dev = netdev_priv(net);

	netif_napi_add(net, &dev->rx_napi, gether_poll, GETHER_NAPI_WEIGHT);

	spin_lock_init(&dev->lock);

	spin_lock_init(&dev->req_lock);

	INIT_WORK(&dev->work, eth_work);
@@ -830,6 +853,7 @@ struct net_device *gether_setup_name_default(const char *netname) 
		return ERR_PTR(-ENOMEM);



	dev = netdev_priv(net);

	netif_napi_add(net, &dev->rx_napi, gether_poll, GETHER_NAPI_WEIGHT);

	spin_lock_init(&dev->lock);

	spin_lock_init(&dev->req_lock);

	INIT_WORK(&dev->work, eth_work);
@@ -1113,6 +1137,7 @@ void gether_disconnect(struct gether *link) 
{

	struct eth_dev		*dev = link->ioport;

	struct usb_request	*req;

	struct sk_buff		*skb;



	WARN_ON(!dev);

	if (!dev)
@@ -1139,6 +1164,12 @@ void gether_disconnect(struct gether *link) 
		spin_lock(&dev->req_lock);

	}

	spin_unlock(&dev->req_lock);



	spin_lock(&dev->rx_frames.lock);

	while ((skb = __skb_dequeue(&dev->rx_frames)))

		dev_kfree_skb_any(skb);

	spin_unlock(&dev->rx_frames.lock);



	link->in_ep->driver_data = NULL;

	link->in_ep->desc = NULL;

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