netdev - Re: [PATCH] ftgmac100: Disable HW checksum generation on AST2500

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Date:   Wed, 9 Oct 2019 14:20:59 -0400
From:   Oskar Senft <osk@...gle.com>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:     Joel Stanley <joel@....id.au>,
        Florian Fainelli <f.fainelli@...il.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Andrew Lunn <andrew@...n.ch>,
        linux-aspeed <linux-aspeed@...ts.ozlabs.org>,
        netdev@...r.kernel.org,
        "openbmc @ lists . ozlabs . org" <openbmc@...ts.ozlabs.org>,
        YueHaibing <yuehaibing@...wei.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vijay Khemka <vijaykhemka@...com>
Subject: Re: [PATCH] ftgmac100: Disable HW checksum generation on AST2500

Does HW in the AST2500 actually perform the HW checksum calculation,
or would that be the responsibility of the NIC that it's talking to
via NC-SI?

(Sorry for the double posting! I had HTML mode enabled by default
which causes the e-mail to be dropped in some places)


On Wed, Oct 9, 2019 at 12:38 AM Benjamin Herrenschmidt
<benh@...nel.crashing.org> wrote:
>
> On Wed, 2019-09-11 at 14:48 +0000, Joel Stanley wrote:
> > Hi Ben,
> >
> > On Tue, 10 Sep 2019 at 22:05, Florian Fainelli <f.fainelli@...il.com>
> > wrote:
> > >
> > > On 9/10/19 2:37 PM, Vijay Khemka wrote:
> > > > HW checksum generation is not working for AST2500, specially with
> > > > IPV6
> > > > over NCSI. All TCP packets with IPv6 get dropped. By disabling
> > > > this
> > > > it works perfectly fine with IPV6.
> > > >
> > > > Verified with IPV6 enabled and can do ssh.
> > >
> > > How about IPv4, do these packets have problem? If not, can you
> > > continue
> > > advertising NETIF_F_IP_CSUM but take out NETIF_F_IPV6_CSUM?
> > >
> > > >
> > > > Signed-off-by: Vijay Khemka <vijaykhemka@...com>
> > > > ---
> > > >  drivers/net/ethernet/faraday/ftgmac100.c | 5 +++--
> > > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/net/ethernet/faraday/ftgmac100.c
> > > > b/drivers/net/ethernet/faraday/ftgmac100.c
> > > > index 030fed65393e..591c9725002b 100644
> > > > --- a/drivers/net/ethernet/faraday/ftgmac100.c
> > > > +++ b/drivers/net/ethernet/faraday/ftgmac100.c
> > > > @@ -1839,8 +1839,9 @@ static int ftgmac100_probe(struct
> > > > platform_device *pdev)
> > > >       if (priv->use_ncsi)
> > > >               netdev->hw_features |= NETIF_F_HW_VLAN_CTAG_FILTER;
> > > >
> > > > -     /* AST2400  doesn't have working HW checksum generation */
> > > > -     if (np && (of_device_is_compatible(np, "aspeed,ast2400-
> > > > mac")))
> > > > +     /* AST2400  and AST2500 doesn't have working HW checksum
> > > > generation */
> > > > +     if (np && (of_device_is_compatible(np, "aspeed,ast2400-
> > > > mac") ||
> > > > +                of_device_is_compatible(np, "aspeed,ast2500-
> > > > mac")))
> >
> > Do you recall under what circumstances we need to disable hardware
> > checksumming?
>
> Any news on this ? AST2400 has no HW checksum logic in HW, AST2500
> should work for IPV4 fine, we should only selectively disable it for
> IPV6.
>
> Can you do an updated patch ?
>
> Cheers,
> Ben.
>