Commit 492f5add authored Dec 22, 2014 by Amir Vadai Committed by David S. Miller Dec 22, 2014

net/mlx4_en: Doorbell is byteswapped in Little Endian archs



iowrite32() will byteswap it's argument on big endian archs.
iowrite32be() will byteswap on little endian archs.
Since we don't want to do this unnecessary byteswap on the fast path,
doorbell is stored in the NIC's native endianness. Using the right
iowrite() according to the arch endianness.

CC: Wei Yang <weiyang@linux.vnet.ibm.com>
CC: David Laight <david.laight@aculab.com>
Fixes: 6a4e8121 ("net/mlx4_en: Avoid calling bswap in tx fast path")
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ea3c9e13

drivers/net/ethernet/mellanox/mlx4/en_tx.c

+11 −1

Original line number	Diff line number	Diff line
		@@ -962,7 +962,17 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff skb, struct net_device dev)
		tx_desc->ctrl.owner_opcode = op_own;
		if (send_doorbell) {
		wmb();
		iowrite32(ring->doorbell_qpn,
		/* Since there is no iowrite*_native() that writes the
		* value as is, without byteswapping - using the one
		* the doesn't do byteswapping in the relevant arch
		* endianness.
		*/
		#if defined(__LITTLE_ENDIAN)
		iowrite32(
		#else
		iowrite32be(
		#endif
		ring->doorbell_qpn,
		ring->bf.uar->map + MLX4_SEND_DOORBELL);
		} else {
		ring->xmit_more++;