Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-10-23 13:40:56 +00:00
Code Issues Packages Projects Releases Wiki Activity

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

Browse Source 
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: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Bjørn Mork 2013-11-01 11:16:49 +01:00 committed by David S. Miller
parent 9fe0234c0b
commit 4d619f625a
1 changed files with 5 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/net/usb/cdc_ncm.c
View File

@ -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)