提交 4d619f62 编写于 作者: B Bjørn Mork 提交者: David S. Miller

net: cdc_ncm: no point in filling up the NTBs if we send ZLPs

Padding NTBs to max size is part of the support for devices
optimizing their DMA transfers. This optimization depends on
max sized NTBs not being ZLP terminated. So we are much better
off dropping the padding if we are going to send a ZLP anyway.

Cc: Alexey Orishko <alexey.orishko@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
上级 9fe0234c
......@@ -800,8 +800,12 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign)
* would be more efficient for USB HS mobile device with DMA
* engine to receive a full size NTB, than canceling DMA
* transfer and receiving a short packet.
*
* This optimization support is pointless if we end up sending
* a ZLP after full sized NTBs.
*/
if (skb_out->len > CDC_NCM_MIN_TX_PKT)
if (!(dev->driver_info->flags & FLAG_SEND_ZLP) &&
skb_out->len > CDC_NCM_MIN_TX_PKT)
memset(skb_put(skb_out, ctx->tx_max - skb_out->len), 0,
ctx->tx_max - skb_out->len);
else if ((skb_out->len % dev->maxpacket) == 0)
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册