uboot-imx

net: davinci_emac: Invalidate only the received portion of a buffer

ATM when receiving a packet the whole buffer is invalidated, this change
optimizes this behaviour.

Signed-off-by: Karl Beldan <karl.beldan+oss@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Mugunthan V N <mugunthanvnm@ti.com>