netdev - Re: [PATCH net-next 4/7] net: dsa: felix: set proper pause frame timers based on link speed

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Message-ID: <20200625165818.GK1551@shell.armlinux.org.uk>
Date:   Thu, 25 Jun 2020 17:58:18 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandru Marginean <alexandru.marginean@....com>,
        Ioana Ciornei <ioana.ciornei@....com>
Subject: Re: [PATCH net-next 4/7] net: dsa: felix: set proper pause frame
 timers based on link speed

On Thu, Jun 25, 2020 at 07:48:23PM +0300, Vladimir Oltean wrote:
> On Thu, 25 Jun 2020 at 19:37, Russell King - ARM Linux admin
> <linux@...linux.org.uk> wrote:
> >
> > On Thu, Jun 25, 2020 at 06:23:28PM +0300, Vladimir Oltean wrote:
> > > From: Vladimir Oltean <vladimir.oltean@....com>
> > >
> > > state->speed holds a value of 10, 100, 1000 or 2500, but
> > > SYS_MAC_FC_CFG_FC_LINK_SPEED expects a value in the range 0, 1, 2 or 3.
> > >
> > > So set the correct speed encoding into this register.
> > >
> > > Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> > > ---
> > >  drivers/net/dsa/ocelot/felix.c | 27 +++++++++++++++++++++++----
> > >  1 file changed, 23 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
> > > index d229cb5d5f9e..da337c63e7ca 100644
> > > --- a/drivers/net/dsa/ocelot/felix.c
> > > +++ b/drivers/net/dsa/ocelot/felix.c
> > > @@ -250,10 +250,25 @@ static void felix_phylink_mac_config(struct dsa_switch *ds, int port,
> > >                          DEV_CLOCK_CFG_LINK_SPEED(OCELOT_SPEED_1000),
> > >                          DEV_CLOCK_CFG);
> > >
> > > -     /* Flow control. Link speed is only used here to evaluate the time
> > > -      * specification in incoming pause frames.
> > > -      */
> > > -     mac_fc_cfg = SYS_MAC_FC_CFG_FC_LINK_SPEED(state->speed);
> > > +     switch (state->speed) {
> > > +     case SPEED_10:
> > > +             mac_fc_cfg = SYS_MAC_FC_CFG_FC_LINK_SPEED(3);
> > > +             break;
> > > +     case SPEED_100:
> > > +             mac_fc_cfg = SYS_MAC_FC_CFG_FC_LINK_SPEED(2);
> > > +             break;
> > > +     case SPEED_1000:
> > > +     case SPEED_2500:
> > > +             mac_fc_cfg = SYS_MAC_FC_CFG_FC_LINK_SPEED(1);
> > > +             break;
> > > +     case SPEED_UNKNOWN:
> > > +             mac_fc_cfg = SYS_MAC_FC_CFG_FC_LINK_SPEED(0);
> > > +             break;
> > > +     default:
> > > +             dev_err(ocelot->dev, "Unsupported speed on port %d: %d\n",
> > > +                     port, state->speed);
> > > +             return;
> > > +     }
> > >
> > >       /* handle Rx pause in all cases, with 2500base-X this is used for rate
> > >        * adaptation.
> > > @@ -265,6 +280,10 @@ static void felix_phylink_mac_config(struct dsa_switch *ds, int port,
> > >                             SYS_MAC_FC_CFG_PAUSE_VAL_CFG(0xffff) |
> > >                             SYS_MAC_FC_CFG_FC_LATENCY_CFG(0x7) |
> > >                             SYS_MAC_FC_CFG_ZERO_PAUSE_ENA;
> > > +
> > > +     /* Flow control. Link speed is only used here to evaluate the time
> > > +      * specification in incoming pause frames.
> > > +      */
> > >       ocelot_write_rix(ocelot, mac_fc_cfg, SYS_MAC_FC_CFG, port);
> >
> > I'm not that happy with the persistence of felix using the legacy
> > method; I can bring a horse to water but can't make it drink comes
> > to mind.  I'm at the point where I don't care _if_ my phylink changes
> > break code that I've asked people to convert and they haven't yet,
> > and I'm planning to send the series that /may/ cause breakage in
> > that regard pretty soon, so the lynx PCS changes can move forward.
> >
> > I even tried to move felix forward by sending a patch for it, and I
> > just gave up with that approach based on your comment.
> >
> > Shrug.
> >
> > --
> > RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> > FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
> 
> The callbacks clearly work the way they are, given the current
> structure of phylink, as proven by the users of this driver. Code that
> isn't there yet simply isn't there yet.
> 
> What you consider "useless churn" and what I consider "useless churn"
> are pretty different things.
> To me, patch 7/7 is the useless churn, that's why it's at the end.
> Patches 1-6 are structured in a way that is compatible with
> backporting to a stable 5.4 tree. Patch 7, not so much.
> 
> The fact that you have such an attitude and you make the effort to
> actually send an email complaining about me using state->speed in
> .mac_config(), when literally 3 patches later I'm moving this
> configuration where you want it to be, is pretty annoying.

I have asked you to update felix _prior_ to my patch update, because
I forsee the possibility for there to be breakage from pushing the
PCS support further forward.  In other words, I see there to be a
dependency between moving forward with PCS support and drivers that
still use the legacy method.

You don't see that, so you constantly bitch and moan.

Please stop being a problem.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!