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Commit 2aba979b authored by Sujeev Dias's avatar Sujeev Dias Committed by Gerrit - the friendly Code Review server
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mhi: dev: netdev: add support for chain skb to reduce cpu mips consumption 



Instead of pushing individual IP packets into a network stack
during napi poll, chain all the skbs into a single skb list and
do a single push to network stack.

CRs-Fixed: 2361266
Change-Id: I620408994295d66635038bd9390988a76783cfb8
Signed-off-by: default avatarSujeev Dias <sdias@codeaurora.org>
parent 1241387c

drivers/bus/mhi/devices/mhi_netdev.c

+50 −1
Original line number Diff line number Diff line
@@ -72,6 +72,10 @@ 
			       __func__, ##__VA_ARGS__); \

} while (0)



struct mhi_net_chain {

	struct sk_buff *head, *tail; /* chained skb */

};



struct mhi_netdev {

	int alias;

	struct mhi_device *mhi_dev;
@@ -86,6 +90,8 @@ struct mhi_netdev { 
	struct mhi_netbuf **netbuf_pool;

	int pool_size; /* must be power of 2 */

	int current_index;

	bool chain_skb;

	struct mhi_net_chain *chain;



	struct dentry *dentry;

	enum MHI_DEBUG_LEVEL msg_lvl;
@@ -332,11 +338,19 @@ static int mhi_netdev_poll(struct napi_struct *napi, int budget) 
	struct mhi_netdev_priv *mhi_netdev_priv = netdev_priv(dev);

	struct mhi_netdev *mhi_netdev = mhi_netdev_priv->mhi_netdev;

	struct mhi_device *mhi_dev = mhi_netdev->mhi_dev;

	struct mhi_net_chain *chain = mhi_netdev->chain;

	int rx_work = 0;



	MSG_VERB("Entered\n");



	rx_work = mhi_poll(mhi_dev, budget);



	/* chained skb, push it to stack */

	if (chain && chain->head) {

		netif_receive_skb(chain->head);

		chain->head = NULL;

	}



	if (rx_work < 0) {

		MSG_ERR("Error polling ret:%d\n", rx_work);

		rx_work = 0;
@@ -626,8 +640,10 @@ static void mhi_netdev_xfer_dl_cb(struct mhi_device *mhi_dev, 
	struct mhi_netdev *mhi_netdev = mhi_device_get_devdata(mhi_dev);

	struct mhi_netbuf *netbuf = mhi_result->buf_addr;

	struct mhi_buf *mhi_buf = &netbuf->mhi_buf;

	struct sk_buff *skb;

	struct net_device *ndev = mhi_netdev->ndev;

	struct device *dev = mhi_dev->dev.parent;

	struct mhi_net_chain *chain = mhi_netdev->chain;



	netbuf->unmap(dev, mhi_buf->dma_addr, mhi_buf->len, DMA_FROM_DEVICE);
@@ -640,7 +656,30 @@ static void mhi_netdev_xfer_dl_cb(struct mhi_device *mhi_dev, 
	ndev->stats.rx_packets++;

	ndev->stats.rx_bytes += mhi_result->bytes_xferd;



	if (unlikely(!chain)) {

		mhi_netdev_push_skb(mhi_netdev, mhi_buf, mhi_result);

		return;

	}



	/* we support chaining */

	skb = alloc_skb(0, GFP_ATOMIC);

	if (likely(skb)) {

		skb_add_rx_frag(skb, 0, mhi_buf->page, 0,

				mhi_result->bytes_xferd, mhi_netdev->mru);

		/* this is first on list */

		if (!chain->head) {

			skb->dev = ndev;

			skb->protocol =

				mhi_netdev_ip_type_trans(*(u8 *)mhi_buf->buf);

			chain->head = skb;

		} else {

			skb_shinfo(chain->tail)->frag_list = skb;

		}



		chain->tail = skb;

	} else {

		__free_pages(mhi_buf->page, mhi_netdev->order);

	}

}



static void mhi_netdev_status_cb(struct mhi_device *mhi_dev, enum MHI_CB mhi_cb)
@@ -721,6 +760,7 @@ static int mhi_netdev_probe(struct mhi_device *mhi_dev, 
	struct device_node *of_node = mhi_dev->dev.of_node;

	int nr_tre;

	char node_name[32];

	bool no_chain;



	if (!of_node)

		return -ENODEV;
@@ -742,6 +782,15 @@ static int mhi_netdev_probe(struct mhi_device *mhi_dev, 
	if ((PAGE_SIZE << mhi_netdev->order) < mhi_netdev->mru)

		return -EINVAL;



	no_chain = of_property_read_bool(of_node, "mhi,disable-chain-skb");

	if (!no_chain) {

		mhi_netdev->chain = devm_kzalloc(&mhi_dev->dev,

						 sizeof(*mhi_netdev->chain),

						 GFP_KERNEL);

		if (!mhi_netdev->chain)

			return -ENOMEM;

	}



	ret = mhi_netdev_enable_iface(mhi_netdev);

	if (ret)

		return ret;