netdev - Re: [PATCH v2 net-next 05/13] net: mscc: ocelot: convert QSYS_SWITCH_PORT_MODE and SYS_PORT

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Date:   Sun, 31 May 2020 00:25:46 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        Alexandru Marginean <alexandru.marginean@....com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        "Madalin Bucur (OSS)" <madalin.bucur@....nxp.com>,
        radu-andrei.bulie@....com, fido_max@...ox.ru,
        Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH v2 net-next 05/13] net: mscc: ocelot: convert
 QSYS_SWITCH_PORT_MODE and SYS_PORT_MODE to regfields

Hi Florian,

On Sun, 31 May 2020 at 00:18, Florian Fainelli <f.fainelli@...il.com> wrote:
>
>
>
> On 5/30/2020 4:51 AM, Vladimir Oltean wrote:
> > From: Vladimir Oltean <vladimir.oltean@....com>
> >
> > Currently Felix and Ocelot share the same bit layout in these per-port
> > registers, but Seville does not. So we need reg_fields for that.
> >
> > Actually since these are per-port registers, we need to also specify the
> > number of ports, and register size per port, and use the regmap API for
> > multiple ports.
> >
> > Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> > ---
> > Changes in v2:
> > None.
>
> [snip]
>
>
> >       /* Core: Enable port for frame transfer */
> > -     ocelot_write_rix(ocelot, QSYS_SWITCH_PORT_MODE_INGRESS_DROP_MODE |
> > -                      QSYS_SWITCH_PORT_MODE_SCH_NEXT_CFG(1) |
> > -                      QSYS_SWITCH_PORT_MODE_PORT_ENA,
> > -                      QSYS_SWITCH_PORT_MODE, port);
> > +     ocelot_fields_write(ocelot, port,
> > +                         QSYS_SWITCH_PORT_MODE_INGRESS_DROP_MODE, 1);
> > +     ocelot_fields_write(ocelot, port,
> > +                         QSYS_SWITCH_PORT_MODE_PORT_ENA, 1);
>
> I am a bit confused throughout this patch sometimes SCH_NEXT_CFG is set
> to 1, sometimes not, this makes it a bit harder to review the
> conversion, assuming this is fine:
>
> Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
> --
> Florian

Yes, this is a subtle point, but it's correct the way it is, and I
didn't want to insist on the details of it, but now that you mentioned
it, let's go.
Seville does not have the QSYS_SWITCH_PORT_MODE_SCH_NEXT_CFG register
field at all. And using the previous API (ocelot_write_rix), we were
only writing 1 for Felix and Ocelot, which was their hardware-default
value, so we weren't changing its value in practice. So the equivalent
with ocelot_fields_write would be to simply not do anything at all for
the SCH_NEXT_CFG field, which is actually something that is required
if we want to support Seville too.

Thank you so much for reviewing the entire series!

-Vladimir