Le mercredi 17 février 2010 à 15:55 +0100, Anatolij Gustschin a écrit :
> MPC5121 FEC requeries 4-byte alignmnent for TX data buffers.
> This patch is a work around that copies misaligned tx packets
> to an aligned skb before sending.
>
> Signed-off-by: John Rigby <jcri...@gmail.com>
> Signed-off-by: Piotr Ziecik <ko...@semihalf.com>
> Signed-off-by: Wolfgang Denk <w...@denx.de>
> Signed-off-by: Anatolij Gustschin <ag...@denx.de>
> ---
> drivers/net/fs_enet/fs_enet-main.c | 44
> ++++++++++++++++++++++++++++++++++++
> 1 files changed, 44 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/fs_enet/fs_enet-main.c
> b/drivers/net/fs_enet/fs_enet-main.c
> index 4297021..166a89d 100644
> --- a/drivers/net/fs_enet/fs_enet-main.c
> +++ b/drivers/net/fs_enet/fs_enet-main.c
> @@ -580,6 +580,37 @@ void fs_cleanup_bds(struct net_device *dev)
>
>
> /**********************************************************************************/
>
> +#ifdef CONFIG_FS_ENET_MPC5121_FEC
> +/*
> + * MPC5121 FEC requeries 4-byte alignment for TX data buffer!
> + */
> +static struct sk_buff *tx_skb_align_workaround(struct net_device *dev,
> + struct sk_buff *skb)
> +{
> + struct sk_buff *new_skb;
> + struct fs_enet_private *fep = netdev_priv(dev);
> +
> + /* Alloc new skb */
> + new_skb = dev_alloc_skb(ENET_RX_FRSIZE + 4);
ENET_RX_FRSIZE looks strange in TX path
Why not using skb->len + 4 instead of ENET_RX_FRSIZE + 4 ?
> + if (!new_skb) {
> + dev_warn(fep->dev, "Memory squeeze, dropping tx packet.\n");
I am just wondering if this is ratelimited ?
> + return NULL;
> + }
> +
> + /* Make sure new skb is properly aligned */
> + skb_align(new_skb, 4);
> +
> + /* Copy data to new skb ... */
> + skb_copy_from_linear_data(skb, new_skb->data, skb->len);
> + skb_put(new_skb, skb->len);
> +
> + /* ... and free an old one */
> + dev_kfree_skb_any(skb);
> +
> + return new_skb;
> +}
> +#endif
> +
> static int fs_enet_start_xmit(struct sk_buff *skb, struct net_device *dev)
> {
> struct fs_enet_private *fep = netdev_priv(dev);
> @@ -588,6 +619,19 @@ static int fs_enet_start_xmit(struct sk_buff *skb,
> struct net_device *dev)
> u16 sc;
> unsigned long flags;
>
> +#ifdef CONFIG_FS_ENET_MPC5121_FEC
> + if (((unsigned long)skb->data) & 0x3) {
> + skb = tx_skb_align_workaround(dev, skb);
> + if (!skb) {
> + /*
> + * We have lost packet due to memory allocation error
> + * in tx_skb_align_workaround(). Hopefully original
> + * skb is still valid, so try transmit it later.
> + */
Could you define 'try to transmit later' ?
Who is responsible to trigger this event ?
> + return NETDEV_TX_BUSY;
> + }
> + }
> +#endif
> spin_lock_irqsave(&fep->tx_lock, flags);
>
> /*
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