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

From: Russell King - ARM Linux admin <[email-masked]>
Date: Thu, 25 Jun 2020 18:53:36 +0100

On Thu, Jun 25, 2020 at 08:06:08PM +0300, Vladimir Oltean wrote:
> On Thu, 25 Jun 2020 at 19:58, Russell King - ARM Linux admin
> <[email-masked]> wrote:
> >
> > 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
> > > <[email-masked]> wrote:
> > > >
> > > > On Thu, Jun 25, 2020 at 06:23:28PM +0300, Vladimir Oltean wrote:
> > > > > From: Vladimir Oltean <[email-masked]>
> > > > >
> > > > > 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 <[email-masked]>
> > > > > ---
> > > > >  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.
> >
> 
> And that's what this patch series is, no?
> Some cleanup needed to be done, and it needed to be done _before_ the
> mac_link_up() conversion. And for things to go quicker, the cleanup
> and the conversion are part of the same series.

Right, which is what I find when I eventually get to patch 7, the patch
that you called above "useless churn."  I'm not going to review patch 7
tonight because of this fiasco.  To pissed off to do a decent job, so
you're just going to have to wait.

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