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Date: Wed, 6 Jun 2012 13:23:28 -0700
From: Stephen Hemminger <shemminger@...tta.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Kirill Smelkov <kirr@....spb.ru>,
David Miller <davem@...emloft.net>,
Mirko Lindner <mlindner@...vell.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] sky2: fix checksum bit management on some chips
On Wed, 06 Jun 2012 22:14:04 +0200
Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Wed, 2012-06-06 at 13:01 -0700, Stephen Hemminger wrote:
> > The newer flavors of Yukon II use a different method for receive
> > checksum offload. This is indicated in the driver by the SKY2_HW_NEW_LE
> > flag. On these newer chips, the BMU_ENA_RX_CHKSUM should not be set.
> >
> > The driver would get incorrectly toggle the bit, enabling the old
> > checksum logic on these chips and cause a BUG_ON() assertion. If
> > receive checksum was toggled via ethtool.
> >
> > Reported-by: Kirill Smelkov <kirr@....spb.ru>
> >
> > Signed-off-by: Stephen Hemminger <shemminger@...tta.com>
> >
> > ---
> > Patch against net-next, please apply to net and stable kernels.
> >
> > --- a/drivers/net/ethernet/marvell/sky2.c 2012-06-06 11:09:38.288440819 -0700
> > +++ b/drivers/net/ethernet/marvell/sky2.c 2012-06-06 11:25:01.275782462 -0700
> > @@ -4381,10 +4381,12 @@ static int sky2_set_features(struct net_
> > struct sky2_port *sky2 = netdev_priv(dev);
> > netdev_features_t changed = dev->features ^ features;
> >
> > - if (changed & NETIF_F_RXCSUM) {
> > - bool on = features & NETIF_F_RXCSUM;
> > - sky2_write32(sky2->hw, Q_ADDR(rxqaddr[sky2->port], Q_CSR),
> > - on ? BMU_ENA_RX_CHKSUM : BMU_DIS_RX_CHKSUM);
> > + if ((changed & NETIF_F_RXCSUM) &&
> > + !(sky2->hw->flags & SKY2_HW_NEW_LE)) {
> > + sky2_write32(sky2->hw,
> > + Q_ADDR(rxqaddr[sky2->port], Q_CSR),
> > + (features & NETIF_F_RXCSUM)
> > + ? BMU_ENA_RX_CHKSUM : BMU_DIS_RX_CHKSUM);
>
> Don't you need to return an error if NETIF_F_RXCSUM could not be
> changed ?
>
>
No, what happens is that on the new chips, the feature flag is already checked
in the receive status processing
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