tree c83e948287802fa31a5b298a4b5fc6aec7342670
parent fbc80823a93c57f2310dacfabfea6c76424552b6
author Giuseppe Cavallaro <peppe.cavallaro@st.com> 1456752458 +0100
committer David S. Miller <davem@davemloft.net> 1456946493 -0500

stmmac: first frame prep at the end of xmit routine

This patch is to fill the first descriptor just before granting
the DMA engine so at the end of the xmit.
The patch takes care about the algorithm adopted to mitigate the
interrupts, then it fixes the last segment in case of no fragments.
Moreover, this new implementation does not pass any "ter" field when
prepare the descriptors because this is not necessary.
The patch also details the memory barrier in the xmit.

As final results, this patch guarantees the same performances
but fixing a case if small datagram are sent. In fact, this
kind of test is impacted if no coalesce is done.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>