netdev - [PATCH net] net/mlx4_en: correct the endianness of doorbell

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Date:	Sun, 30 Nov 2014 10:43:51 +0800
From:	Wei Yang <weiyang@...ux.vnet.ibm.com>
To:	netdev@...r.kernel.org
Cc:	davem@...emloft.net, gideonn@...lanox.com,
	Wei Yang <weiyang@...ux.vnet.ibm.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Amir Vadai <amirv@...lanox.com>
Subject: [PATCH net] net/mlx4_en: correct the endianness of doorbell_qpn on big endian platform

In commit 6a4e812 (net/mlx4_en: Avoid calling bswap in tx fast path), we store
doorbell_qpn in big endian to avoid bswap(). Then we try to write it directly
by iowrite32() instead of iowrite32be().

This works fine on little endian platform, while has some problem on big
endian platform. Here is the definition in general:

	#define iowrite32(v, addr)	writel((v), (addr))
	#define writel(b,addr)		__raw_writel(__cpu_to_le32(b),addr)

On little endian platform, the value is not swapped before write. While on big
endian platform, the value is swapped. This is not expected to happen.

This patch does the swap on big endian platform before it is written.

Signed-off-by: Wei Yang <weiyang@...ux.vnet.ibm.com>
CC: Eric Dumazet <edumazet@...gle.com>
CC: Amir Vadai <amirv@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_tx.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index 454d9fe..76f028b 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -954,7 +954,7 @@ 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,
+			iowrite32(__cpu_to_le32(ring->doorbell_qpn),
 				  ring->bf.uar->map + MLX4_SEND_DOORBELL);
 		} else {
 			ring->xmit_more++;
-- 
1.7.9.5

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