tree 77db9952a2c424b51902d829666a3c9638f1d8eb
parent 95eb930a40a0973f9b984d87a4986bb81f897ede
author Niklas Cassel <niklas.cassel@axis.com> 1519681628 +0100
committer David S. Miller <davem@davemloft.net> 1519759690 -0500

net: stmmac: ensure that the device has released ownership before reading data

According to Documentation/memory-barriers.txt, we need to use a
dma_rmb() after reading the status/own bit, to ensure that all
descriptor fields are read after reading the own bit.

This way, we ensure that the DMA engine is done with the DMA
descriptor before we read the other descriptor fields, e.g. reading
the tx hardware timestamp (if PTP is enabled).

Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>