From: "Russell King (Oracle)" <linux@armlinux•org.uk>
To: Vladimir Oltean <vladimir.oltean@nxp•com>
Cc: "netdev@vger•kernel.org" <netdev@vger•kernel.org>,
Claudiu Manoil <claudiu.manoil@nxp•com>,
Alexandre Belloni <alexandre.belloni@bootlin•com>,
"UNGLinuxDriver@microchip•com" <UNGLinuxDriver@microchip•com>,
Heiner Kallweit <hkallweit1@gmail•com>,
Sean Anderson <sean.anderson@seco•com>,
Colin Foster <colin.foster@in-advantage•com>,
Andrew Lunn <andrew@lunn•ch>,
Vivien Didelot <vivien.didelot@gmail•com>,
Florian Fainelli <f.fainelli@gmail•com>,
"David S. Miller" <davem@davemloft•net>,
Eric Dumazet <edumazet@google•com>,
Jakub Kicinski <kuba@kernel•org>, Paolo Abeni <pabeni@redhat•com>
Subject: Re: [PATCH net-next 4/4] net: dsa: remove phylink_validate() method
Date: Tue, 1 Nov 2022 15:42:46 +0000 [thread overview]
Message-ID: <Y2E+dvH+zk1/QPpB@shell.armlinux.org.uk> (raw)
In-Reply-To: <20221101124035.tqlmxvyrqpaqn63h@skbuf>
On Tue, Nov 01, 2022 at 12:40:36PM +0000, Vladimir Oltean wrote:
> On Tue, Nov 01, 2022 at 12:01:32PM +0000, Russell King (Oracle) wrote:
> > On Tue, Nov 01, 2022 at 01:48:06PM +0200, Vladimir Oltean wrote:
> > > Not all DSA drivers provide config->mac_capabilities, for example
> > > mv88e6060, lan9303 and vsc73xx don't. However, there have been users of
> > > those drivers on recent kernels and no one reported that they fail to
> > > establish a link, so I'm guessing that they work (somehow). But I must
> > > admit I don't understand why phylink_generic_validate() works when
> > > mac_capabilities=0. Anyway, these drivers did not provide a
> > > phylink_validate() method before and do not provide one now, so nothing
> > > changes for them.
> >
> > There is a specific exception:
> >
> > When config->mac_capabilities is zero, and there is no phylink_validate()
> > function, dsa_port_phylink_validate() becomes a no-op, and the no-op
> > case basically means "everything is allowed", which is how things worked
> > before the generic validation was added, as you will see from commit
> > 5938bce4b6e2 ("net: dsa: support use of phylink_generic_validate()").
> >
> > Changing this as you propose below will likely break these drivers.
> >
> > A safer change would be to elimate ds->ops->phylink_validate, leaving
> > the call to phylink_generic_validate() conditional on mac_capabilities
> > having been filled in - which will save breaking these older drivers.
>
> Yes, this is correct, thanks; our emails crossed.
>
> Between keeping a no-op phylink_validate() for these drivers and filling
> in mac_capabilities for them, to remove this extra code path in DSA,
> what would be preferred?
My stance has always been - if we don't know the answer to a question
that affects a code path in a way we want to, we can't modify that code
path. That said:
> The 3 drivers I mentioned could all get a blanket MAC_10 | MAC_100 |
> MAC1000FD | MAC_ASYM_PAUSE | MAC_SYM_PAUSE to keep advertising what they
> did, even if this may or may not be 100% correct (lan9303 and mv88e6060
> are not gigabit, and I don't know if they do flow control properly), but
> these issues are not new.
Would almost be no different from what we do today. The exception would
be the lack of 1000HD, which I think should be included even though it
isn't common - because currently it will be included.
I also think that if we're going down this route and putting code to set
those capabilities in the DSA drivers, they need to be accompanied with
a comment stating that they are a guess and may not be correct.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2022-11-01 15:42 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-01 11:48 [PATCH net-next 0/4] Remove phylink_validate() from Felix DSA driver Vladimir Oltean
2022-11-01 11:48 ` [PATCH net-next 1/4] net: phy: aquantia: add AQR112 and AQR412 PHY IDs Vladimir Oltean
2022-11-01 15:36 ` Sean Anderson
2022-11-03 11:39 ` Vladimir Oltean
2022-11-01 11:48 ` [PATCH net-next 2/4] net: dsa: felix: use phylink_generic_validate() Vladimir Oltean
2022-11-01 11:48 ` [PATCH net-next 3/4] net: mscc: ocelot: drop workaround for forcing RX flow control Vladimir Oltean
2022-11-01 11:48 ` [PATCH net-next 4/4] net: dsa: remove phylink_validate() method Vladimir Oltean
2022-11-01 11:59 ` Vladimir Oltean
2022-11-01 12:01 ` Russell King (Oracle)
2022-11-01 12:40 ` Vladimir Oltean
2022-11-01 15:42 ` Russell King (Oracle) [this message]
2022-11-04 11:24 ` Russell King (Oracle)
2022-11-04 11:35 ` Russell King (Oracle)
2022-11-04 13:32 ` Vladimir Oltean
2022-11-04 14:01 ` Russell King (Oracle)
2022-11-04 14:25 ` Vladimir Oltean
2022-11-04 14:48 ` Russell King (Oracle)
2022-11-04 15:33 ` Vladimir Oltean
2022-11-04 15:40 ` Florian Fainelli
2022-11-04 16:35 ` Russell King (Oracle)
2022-11-06 1:04 ` Florian Fainelli
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