netdev - Re: [PATCH] mlx4_en: fix endianness with blue frame support

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Date:	Mon, 10 Oct 2011 13:46:54 -0300
From:	Thadeu Lima de Souza Cascardo <cascardo@...ux.vnet.ibm.com>
To:	netdev@...r.kernel.org
Cc:	linuxppc-dev@...ts.ozlabs.org, Eli Cohen <eli@....mellanox.co.il>,
	Yevgeny Petrilin <yevgenyp@...lanox.co.il>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH] mlx4_en: fix endianness with blue frame support

On Mon, Oct 10, 2011 at 01:42:23PM -0300, Thadeu Lima de Souza Cascardo wrote:
> The doorbell register was being unconditionally swapped. In x86, that
> meant it was being swapped to BE and written to the descriptor and to
> memory, depending on the case of blue frame support or writing to
> doorbell register. On PPC, this meant it was being swapped to LE and
> then swapped back to BE while writing to the register. But in the blue
> frame case, it was being written as LE to the descriptor.
> 
> The fix is not to swap doorbell unconditionally, write it to the
> register as BE and convert it to BE when writing it to the descriptor.
> 
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...ux.vnet.ibm.com>
> Reported-by: Richard Hendrickson <richhend@...ibm.com>
> Cc: Eli Cohen <eli@....mellanox.co.il>
> Cc: Yevgeny Petrilin <yevgenyp@...lanox.co.il>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> ---

So I tested this patch and it works for me. Thanks Ben and Eli for
finding out the problem with doorbell in the descriptor.

Regards,
Cascardo.

>  drivers/net/mlx4/en_tx.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/mlx4/en_tx.c b/drivers/net/mlx4/en_tx.c
> index 6e03de0..f76ab6b 100644
> --- a/drivers/net/mlx4/en_tx.c
> +++ b/drivers/net/mlx4/en_tx.c
> @@ -172,7 +172,7 @@ int mlx4_en_activate_tx_ring(struct mlx4_en_priv *priv,
>  	memset(ring->buf, 0, ring->buf_size);
> 
>  	ring->qp_state = MLX4_QP_STATE_RST;
> -	ring->doorbell_qpn = swab32(ring->qp.qpn << 8);
> +	ring->doorbell_qpn = ring->qp.qpn << 8;
> 
>  	mlx4_en_fill_qp_context(priv, ring->size, ring->stride, 1, 0, ring->qpn,
>  				ring->cqn, &ring->context);
> @@ -791,7 +791,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
>  		skb_orphan(skb);
> 
>  	if (ring->bf_enabled && desc_size <= MAX_BF && !bounce && !vlan_tag) {
> -		*(u32 *) (&tx_desc->ctrl.vlan_tag) |= ring->doorbell_qpn;
> +		*(__be32 *) (&tx_desc->ctrl.vlan_tag) |= cpu_to_be32(ring->doorbell_qpn);
>  		op_own |= htonl((bf_index & 0xffff) << 8);
>  		/* Ensure new descirptor hits memory
>  		* before setting ownership of this descriptor to HW */
> @@ -812,7 +812,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
>  		wmb();
>  		tx_desc->ctrl.owner_opcode = op_own;
>  		wmb();
> -		writel(ring->doorbell_qpn, ring->bf.uar->map + MLX4_SEND_DOORBELL);
> +		iowrite32be(ring->doorbell_qpn, ring->bf.uar->map + MLX4_SEND_DOORBELL);
>  	}
> 
>  	/* Poll CQ here */
> -- 
> 1.7.4.4
> 

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