linux-kernel - Re: [EXT] Re: [PATCH net-next 3/5] net: mvpp2: cls: Use RSS contexts to handle RSS tables

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Message-ID: <CAGnkfhx8fEZCoLPzGxSzQnj1ZWcQtBMn+g_jO1Jxc4zF7pQwjQ@mail.gmail.com>
Date:   Sat, 9 May 2020 15:14:05 +0200
From:   Matteo Croce <mcroce@...hat.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     Stefan Chulski <stefanc@...vell.com>,
        "David S . Miller" <davem@...emloft.net>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        "gregory.clement@...tlin.com" <gregory.clement@...tlin.com>,
        "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
        Nadav Haklai <nadavh@...vell.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [EXT] Re: [PATCH net-next 3/5] net: mvpp2: cls: Use RSS contexts
 to handle RSS tables

On Sat, May 9, 2020 at 1:45 PM Russell King - ARM Linux admin
<linux@...linux.org.uk> wrote:
>
> On Sat, May 09, 2020 at 11:15:58AM +0000, Stefan Chulski wrote:
> >
> >
> > > -----Original Message-----
> > > From: Matteo Croce <mcroce@...hat.com>
> > > Sent: Saturday, May 9, 2020 3:13 AM
> > > To: David S . Miller <davem@...emloft.net>
> > > Cc: Maxime Chevallier <maxime.chevallier@...tlin.com>; netdev
> > > <netdev@...r.kernel.org>; LKML <linux-kernel@...r.kernel.org>; Antoine
> > > Tenart <antoine.tenart@...tlin.com>; Thomas Petazzoni
> > > <thomas.petazzoni@...tlin.com>; gregory.clement@...tlin.com;
> > > miquel.raynal@...tlin.com; Nadav Haklai <nadavh@...vell.com>; Stefan
> > > Chulski <stefanc@...vell.com>; Marcin Wojtas <mw@...ihalf.com>; Linux
> > > ARM <linux-arm-kernel@...ts.infradead.org>; Russell King - ARM Linux admin
> > > <linux@...linux.org.uk>
> > > Subject: [EXT] Re: [PATCH net-next 3/5] net: mvpp2: cls: Use RSS contexts to
> > > handle RSS tables
> > >
> > > Hi,
> > >
> > > What do you think about temporarily disabling it like this?
> > >
> > > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > > @@ -5775,7 +5775,8 @@ static int mvpp2_port_probe(struct platform_device
> > > *pdev,
> > >                             NETIF_F_HW_VLAN_CTAG_FILTER;
> > >
> > >         if (mvpp22_rss_is_supported()) {
> > > -               dev->hw_features |= NETIF_F_RXHASH;
> > > +               if (port->phy_interface != PHY_INTERFACE_MODE_SGMII)
> > > +                       dev->hw_features |= NETIF_F_RXHASH;
> > >                 dev->features |= NETIF_F_NTUPLE;
> > >         }
> > >
> > >
> > > David, is this "workaround" too bad to get accepted?
> >
> > Not sure that RSS related to physical interface(SGMII), better just remove NETIF_F_RXHASH as "workaround".
>
> Hmm, I'm not sure this is the right way forward.  This patch has the
> effect of disabling:
>
> d33ec4525007 ("net: mvpp2: add an RSS classification step for each flow")
>
> but the commit you're pointing at which caused the regression is:
>
> 895586d5dc32 ("net: mvpp2: cls: Use RSS contexts to handle RSS tables")
>
>

Hi,

When git bisect pointed to 895586d5dc32 ("net: mvpp2: cls: Use RSS
contexts to handle RSS tables"), which was merged
almost an year after d33ec4525007 ("net: mvpp2: add an RSS
classification step for each flow"), so I assume that between these
two commits either the feature was working or it was disable and we
didn't notice

Without knowing what was happening, which commit should my Fixes tag point to?

Regards,
-- 
Matteo Croce
per aspera ad upstream