netdev - Re: [PATCH net-next 2/4 v4] net: dsa: rtl8366rb: Support flood control

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Message-ID: <CACRpkdY7GUN+-_d-Af8k0h2TOfiBFg=JH9WYud1-A1dLgEFjNQ@mail.gmail.com>
Date:   Tue, 5 Oct 2021 00:22:16 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Alvin Šipraga <ALSI@...g-olufsen.dk>
Cc:     Vladimir Oltean <olteanv@...il.com>, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Mauri Sandberg <sandberg@...lfence.com>,
        DENG Qingfang <dqfext@...il.com>
Subject: Re: [PATCH net-next 2/4 v4] net: dsa: rtl8366rb: Support flood control

On Thu, Sep 30, 2021 at 11:09 AM Alvin Šipraga <ALSI@...g-olufsen.dk> wrote:
> On 9/29/21 11:57 PM, Vladimir Oltean wrote:
> > On Wed, Sep 29, 2021 at 11:03:47PM +0200, Linus Walleij wrote:

> >> Now that we have implemented bridge flag handling we can easily
> >> support flood control as well so let's do it.

> >> +/* Storm registers are for flood control
> >> + *
> >> + * 02e2 and 02e3 are defined in the header for the RTL8366RB API
> >> + * but there are no usage examples. The implementation only activates
> >> + * the filter per port in the CTRL registers.
> >
> > The "filter" word bothers me a bit.
> > Are these settings applied on ingress or on egress? If you have
> > RTL8366RB_STORM_BC_CTRL == BIT(0) | BIT(1), and a broadcast packet is
> > received on port 2, then
> >
> > (a) is it received or dropped?
> > (b) is it forwarded to port 0 and 1?
> > (c) is it forwarded to port 3?
>
> Linus, are you sure these STORM_... registers are the right ones to
> control flooding? The doc from Realtek[1] talks briefly about this storm
> control feature, but it seems to be related to rate limiting, not actual
> flooding behaviour.

You're probably right. I'll just drop this patch for now.

Yours,
Linus Walleij