Newer versions of the PCIe microcode support writing back the
position of the TX pointer back into host memory.  This speeds
up TX completions, because we avoid a read from device memory
(replacing PCIe read with DMA coherent read).
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NFei Qin <fei.qin@corigine.com>
Signed-off-by: NSimon Horman <simon.horman@corigine.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>