Re: [PATCH net-next v3 0/9] net: phy: add Lynx PCS MDIO module

From: Vladimir Oltean <olteanv@gmail.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Ioana Ciornei <ioana.ciornei@nxp.com>,
	netdev <netdev@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Vladimir Oltean <vladimir.oltean@nxp.com>,
	Claudiu Manoil <claudiu.manoil@nxp.com>,
	Alexandru Marginean <alexandru.marginean@nxp.com>,
	Michael Walle <michael@walle.cc>, Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>
Subject: Re: [PATCH net-next v3 0/9] net: phy: add Lynx PCS MDIO module
Date: Mon, 22 Jun 2020 12:34:25 +0300	[thread overview]
Message-ID: <CA+h21hq146U6Zb38Nrc=BKwMu4esNtpK5g79oojxVmGs5gLcYg@mail.gmail.com> (raw)
In-Reply-To: <20200622092944.GB1551@shell.armlinux.org.uk>

On Mon, 22 Jun 2020 at 12:29, Russell King - ARM Linux admin
<linux@armlinux.org.uk> wrote:
>
> On Mon, Jun 22, 2020 at 01:54:42AM +0300, Ioana Ciornei wrote:
> > Add support for the Lynx PCS as a separate module in drivers/net/phy/.
> > The advantage of this structure is that multiple ethernet or switch
> > drivers used on NXP hardware (ENETC, Felix DSA switch etc) can share the
> > same implementation of PCS configuration and runtime management.
> >
> > The PCS is represented as an mdio_device and the callbacks exported are
> > highly tied with PHYLINK and can't be used without it.
> >
> > The first 3 patches add some missing pieces in PHYLINK and the locked
> > mdiobus write accessor. Next, the Lynx PCS MDIO module is added as a
> > standalone module. The majority of the code is extracted from the Felix
> > DSA driver. The last patch makes the necessary changes in the Felix
> > driver in order to use the new common PCS implementation.
> >
> > At the moment, USXGMII (only with in-band AN and speeds up to 2500),
> > SGMII, QSGMII (with and without in-band AN) and 2500Base-X (only w/o
> > in-band AN) are supported by the Lynx PCS MDIO module since these were
> > also supported by Felix and no functional change is intended at this
> > time.
>
> Overall, I think we need to sort out the remaining changes in phylink
> before moving forward with this patch set - I've made some progress
> with Florian and the Broadcom DSA switches late last night.  I'm now
> working on updating the felix DSA driver.
>

What needs to be done in the felix driver that is not part of this
series? Maybe you could review this instead?

> There's another reason - having looked at the work I did with this
> same PHY, I think you are missing configuration of the link timer,
> which is different in SGMII and 1000BASE-X.  Please can you look at
> the code I came up with?  "dpaa2-mac: add 1000BASE-X/SGMII PCS support".
>
> Thanks.
>

felix does not have support code for 1000base-x, so I think it's
natural to not clutter this series with things like that.
Things like USXGMII up to 10G, 10GBase-R, are also missing, for much
of the same reason - we wanted to make no functional change to the
existing code, precisely because we wanted it to go in quickly. There
are multiple things that are waiting for it:
- Michael Walle's enetc patches are going to use pcs-lynx
- The new Seville driver will use pcs-lynx

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

Thanks,
-Vladimir