On Wed, Jul 31, 2013 at 7:12 PM, Oliver Neukum [off-list ref] wrote:

On Wed, 2013-07-31 at 18:51 +0800, Ming Lei wrote:

quoted

Hi,

This patchset allows drivers to pass sg buffers which size can't be divided
by max packet size of endpoint if the host controllers support this kind
of sg buffers.

Cool. One question though. It makes sense to use sg only
if all elements are in memory capable of DMA. It seems to be possible
to have HCs which can do unlimited sg but are limited to 32bit DMA.

For current usbnet devices which supports TSO, one header need to add
before skb->data from network stack, so basically the first two elements aren't
OK for other HCs(EHCI/UHCI/...) to DMA from SG.


Thanks,
--
Ming Le