Re: sky2 large MTU problems...

["Daniel J Blueman" <daniel.blueman@gmail.com>]

Hi Stephen,

I can confirm that I am unable to reproduce any of the problems I was
seeing - it works as expected all the way up to the sky2 maximum MTU
size of 9000. Fantastic!

Thanks again,
 Daniel

On 22/05/06, Stephen Hemminger <shemminger@osdl.org> wrote:
> Try this, not completely baked yet though..
>
> --- sky2.orig/drivers/net/sky2.c        2006-05-22 10:23:51.000000000 -0700
> +++ sky2/drivers/net/sky2.c     2006-05-22 11:30:50.000000000 -0700
> @@ -636,8 +636,10 @@
>                     TX_BACK_OFF_LIM(TX_BOF_LIM_DEF));
>
>         /* serial mode register */
> -       reg = DATA_BLIND_VAL(DATA_BLIND_DEF) |
> -               GM_SMOD_VLAN_ENA | IPG_DATA_VAL(IPG_DATA_DEF);
> +       reg = DATA_BLIND_VAL(DATA_BLIND_DEF) |IPG_DATA_VAL(IPG_DATA_DEF);
> +#ifdef SKY2_VLAN_TAG_USED
> +       reg |= GM_SMOD_VLAN_ENA;
> +#endif
>
>         if (hw->dev[port]->mtu > ETH_DATA_LEN)
>                 reg |= GM_SMOD_JUMBO_ENA;
> @@ -979,6 +981,7 @@
>         struct sky2_hw *hw = sky2->hw;
>         unsigned rxq = rxqaddr[sky2->port];
>         int i;
> +       unsigned thresh;
>
>         sky2->rx_put = sky2->rx_next = 0;
>         sky2_qset(hw, rxq);
> @@ -1003,9 +1006,22 @@
>                 sky2_rx_add(sky2, re->mapaddr);
>         }
>
> -       /* Truncate oversize frames */
> -       sky2_write16(hw, SK_REG(sky2->port, RX_GMF_TR_THR), sky2->rx_bufsize - 8);
> -       sky2_write32(hw, SK_REG(sky2->port, RX_GMF_CTRL_T), RX_TRUNC_ON);
> +
> +       /*
> +        * The receiver hangs gets stuck if it receives frames larger than the
> +        * packet buffer. As a workaround, truncate oversize frames, but
> +        * truncate register is to 9 bits, so if you do jumbo frames
> +        * you better get the MTU right.
> +        */
> +       thresh = (ALIGN(sky2->netdev->mtu + ETH_HLEN, 4)  - 8)/4;
> +
> +       if (thresh > 0x1ff)
> +               sky2_write32(hw, SK_REG(sky2->port, RX_GMF_CTRL_T), RX_TRUNC_OFF);
> +       else {
> +               sky2_write16(hw, SK_REG(sky2->port, RX_GMF_TR_THR), thresh);
> +               sky2_write32(hw, SK_REG(sky2->port, RX_GMF_CTRL_T), RX_TRUNC_ON);
> +       }
> +
>
>         /* Tell chip about available buffers */
>         sky2_write16(hw, Y2_QADDR(rxq, PREF_UNIT_PUT_IDX), sky2->rx_put);
> @@ -1754,7 +1770,7 @@
>   */
>  static inline unsigned sky2_buf_size(int mtu)
>  {
> -       return ALIGN(mtu + ETH_HLEN + VLAN_HLEN, 8) + 8;
> +       return ALIGN(mtu + ETH_HLEN, 8) + 8;
>  }
>
>  static int sky2_change_mtu(struct net_device *dev, int new_mtu)
> @@ -1792,8 +1808,10 @@
>
>         dev->mtu = new_mtu;
>         sky2->rx_bufsize = sky2_buf_size(new_mtu);
> -       mode = DATA_BLIND_VAL(DATA_BLIND_DEF) |
> -               GM_SMOD_VLAN_ENA | IPG_DATA_VAL(IPG_DATA_DEF);
> +       mode = DATA_BLIND_VAL(DATA_BLIND_DEF) |IPG_DATA_VAL(IPG_DATA_DEF);
> +#ifdef SKY2_VLAN_TAG_USED
> +       mode |= GM_SMOD_VLAN_ENA;
> +#endif
>
>         if (dev->mtu > ETH_DATA_LEN)
>                 mode |= GM_SMOD_JUMBO_ENA;
--
Daniel J Blueman
-
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