From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Subject: [PATCH v2 3/4] USBNET: support DMA SG Date: Mon, 5 Aug 2013 16:47:02 +0800 Message-ID: <1375692423-9497-4-git-send-email-ming.lei@canonical.com> References: <1375692423-9497-1-git-send-email-ming.lei@canonical.com> Cc: Oliver Neukum , Sarah Sharp , netdev@vger.kernel.org, linux-usb@vger.kernel.org, Ming Lei , Eric Dumazet , Ben Hutchings , Grant Grundler , Freddy Xin , Alan Stern To: "David S. Miller" , Greg Kroah-Hartman Return-path: Received: from mail-pd0-f177.google.com ([209.85.192.177]:53568 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754780Ab3HEIsD (ORCPT ); Mon, 5 Aug 2013 04:48:03 -0400 In-Reply-To: <1375692423-9497-1-git-send-email-ming.lei@canonical.com> Sender: netdev-owner@vger.kernel.org List-ID: This patch introduces support of DMA SG if the USB host controller which usbnet device is attached to is capable of building packet from discontinuous buffers. The patch supports passing the skb fragment buffers to usb stack directly via urb->sg. Cc: Eric Dumazet Cc: Ben Hutchings Cc: Grant Grundler Cc: Freddy Xin Cc: Oliver Neukum Cc: Alan Stern Signed-off-by: Ming Lei --- drivers/net/usb/usbnet.c | 39 +++++++++++++++++++++++++++++++++++++-- include/linux/usb/usbnet.h | 1 + 2 files changed, 38 insertions(+), 2 deletions(-) diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index e4811d7..615d78e 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -1232,6 +1232,37 @@ EXPORT_SYMBOL_GPL(usbnet_tx_timeout); /*-------------------------------------------------------------------------*/ +static int build_dma_sg(const struct sk_buff *skb, struct urb *urb) +{ + unsigned num_sgs, total_len = 0; + int i, s = 0; + + num_sgs = skb_shinfo(skb)->nr_frags + 1; + if (num_sgs == 1) + return 0; + + urb->sg = kmalloc(num_sgs * sizeof(struct scatterlist), GFP_ATOMIC); + if (!urb->sg) + return -ENOMEM; + + urb->num_sgs = num_sgs; + sg_init_table(urb->sg, urb->num_sgs); + + sg_set_buf(&urb->sg[s++], skb->data, skb_headlen(skb)); + total_len += skb_headlen(skb); + + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + struct skb_frag_struct *f = &skb_shinfo(skb)->frags[i]; + + total_len += skb_frag_size(f); + sg_set_page(&urb->sg[i + s], f->page.p, f->size, + f->page_offset); + } + urb->transfer_buffer_length = total_len; + + return 1; +} + netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, struct net_device *net) { @@ -1258,7 +1289,6 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, goto drop; } } - length = skb->len; if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) { netif_dbg(dev, tx_err, dev->net, "no urb\n"); @@ -1268,10 +1298,14 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, entry = (struct skb_data *) skb->cb; entry->urb = urb; entry->dev = dev; - entry->length = length; usb_fill_bulk_urb (urb, dev->udev, dev->out, skb->data, skb->len, tx_complete, skb); + if (dev->can_dma_sg) { + if (build_dma_sg(skb, urb) < 0) + goto drop; + } + entry->length = length = urb->transfer_buffer_length; /* don't assume the hardware handles USB_ZERO_PACKET * NOTE: strictly conforming cdc-ether devices should expect @@ -1391,6 +1425,7 @@ static void usbnet_bh (unsigned long param) rx_process (dev, skb); continue; case tx_done: + kfree(entry->urb->sg); case rx_cleanup: usb_free_urb (entry->urb); dev_kfree_skb (skb); diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h index 8fbc008..9cb2fe8 100644 --- a/include/linux/usb/usbnet.h +++ b/include/linux/usb/usbnet.h @@ -35,6 +35,7 @@ struct usbnet { unsigned char suspend_count; unsigned char pkt_cnt, pkt_err; unsigned short rx_qlen, tx_qlen; + unsigned can_dma_sg:1; /* i/o info: pipes etc */ unsigned in, out; -- 1.7.9.5