Renesas Ethernet AVB controller requires that all data are aligned on 4-byte
boundary. While it's easily achievable for the RX data with the help of
skb_reserve() (we even align on 128-byte boundary as recommended by the manual),
we can't do the same with the TX data, and it always comes unaligned from
the networking core. Originally we solved it an easy way, copying all packet
to a preallocated aligned buffer; however, it's enough to copy only up to
3 first bytes from each packet, doing the transfer using 2 TX descriptors
instead of just 1. Here's an implementation of the new TX algorithm that
significantly reduces the driver's memory requirements.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2f45d1902a