From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Steen Hegelund <steen.hegelund@microchip.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Lars Povlsen <lars.povlsen@microchip.com>,
Bjarni Jonasson <bjarni.jonasson@microchip.com>,
Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Microsemi List <microsemi@lists.bootlin.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver
Date: Sun, 29 Nov 2020 10:52:45 +0000 [thread overview]
Message-ID: <20201129105245.GG1605@shell.armlinux.org.uk> (raw)
In-Reply-To: <20201128222828.GQ1551@shell.armlinux.org.uk>
On Sat, Nov 28, 2020 at 10:28:28PM +0000, Russell King - ARM Linux admin wrote:
> On Sat, Nov 28, 2020 at 08:06:16PM +0100, Andrew Lunn wrote:
> > > +static void sparx5_phylink_mac_config(struct phylink_config *config,
> > > + unsigned int mode,
> > > + const struct phylink_link_state *state)
> > > +{
> > > + struct sparx5_port *port = netdev_priv(to_net_dev(config->dev));
> > > + struct sparx5_port_config conf;
> > > + int err = 0;
> > > +
> > > + conf = port->conf;
> > > + conf.autoneg = state->an_enabled;
> > > + conf.pause = state->pause;
> > > + conf.duplex = state->duplex;
> > > + conf.power_down = false;
> > > + conf.portmode = state->interface;
> > > +
> > > + if (state->speed == SPEED_UNKNOWN) {
> > > + /* When a SFP is plugged in we use capabilities to
> > > + * default to the highest supported speed
> > > + */
> >
> > This looks suspicious.
>
> Yes, it looks highly suspicious. The fact that
> sparx5_phylink_mac_link_up() is empty, and sparx5_phylink_mac_config()
> does all the work suggests that this was developed before the phylink
> re-organisation, and this code hasn't been updated for it.
>
> Any new code for the kernel really ought to be updated for the new
> phylink methodology before it is accepted.
>
> Looking at sparx5_port_config(), it also seems to use
> PHY_INTERFACE_MODE_1000BASEX for both 1000BASE-X and 2500BASE-X. All
> very well for the driver to do that internally, but it's confusing
> when it comes to reviewing this stuff, especially when people outside
> of the driver (such as myself) reviewing it need to understand what's
> going on with the configuration.
There are other issues too.
Looking at sparx5_get_1000basex_status(), we have:
+ status->link = DEV2G5_PCS1G_LINK_STATUS_LINK_STATUS_GET(value) |
+ DEV2G5_PCS1G_LINK_STATUS_SYNC_STATUS_GET(value);
Why is the link status the logical OR of these?
+ if ((lp_abil >> 8) & 1) /* symmetric pause */
+ status->pause = MLO_PAUSE_RX | MLO_PAUSE_TX;
+ if (lp_abil & (1 << 7)) /* asymmetric pause */
+ status->pause |= MLO_PAUSE_RX;
is actually wrong, and I see I need to improve the documentation for
mac_pcs_get_state(). The intention in the documentation was concerning
hardware that indicated the _resolved_ status of pause modes. It was
not intended that drivers resolve the pause modes themselves.
Even so, the above is still wrong; it takes no account of what is being
advertised at the local end. If one looks at the implementation in
phylink_decode_c37_word(), one will notice there is code to deal with
this.
I think we ought to make phylink_decode_c37_word() and
phylink_decode_sgmii_word() public functions, and then this driver can
use these helpers to decode the link partner advertisement to the
phylink state.
Does the driver need to provide an ethtool .get_link function? That
seems to bypass phylink. Why can't ethtool_op_get_link() be used?
I think if ethtool_op_get_link() is used, we then have just one caller
for sparx5_get_port_status(), which means "struct sparx5_port_status"
can be eliminated and the code cleaned up to use the phylink decoding
helpers.
--
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:[~2020-11-29 10:59 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-27 13:33 [RFC PATCH 0/3] net: Adding the Sparx5 Switch Driver Steen Hegelund
2020-11-27 13:33 ` [RFC PATCH 1/3] dt-bindings: net: sparx5: Add sparx5-switch bindings Steen Hegelund
2020-11-27 17:00 ` Andrew Lunn
2020-11-30 13:09 ` Steen Hegelund
2020-11-30 14:05 ` Andrew Lunn
2020-11-30 15:33 ` Steen Hegelund
2020-11-27 13:33 ` [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver Steen Hegelund
2020-11-27 17:15 ` Andrew Lunn
2020-11-30 13:13 ` Steen Hegelund
2020-12-07 13:33 ` Jiri Pirko
2020-11-28 18:45 ` Andrew Lunn
2020-11-30 13:17 ` Steen Hegelund
2020-11-28 19:03 ` Andrew Lunn
2020-11-30 13:28 ` Steen Hegelund
2020-11-30 15:34 ` Andrew Lunn
2020-11-28 19:06 ` Andrew Lunn
2020-11-28 19:37 ` Russell King - ARM Linux admin
2020-11-28 20:07 ` Alexandre Belloni
2020-11-28 20:21 ` Andrew Lunn
2020-11-28 22:28 ` Russell King - ARM Linux admin
2020-11-29 10:52 ` Russell King - ARM Linux admin [this message]
2020-11-29 11:28 ` Russell King - ARM Linux admin
2020-11-30 14:39 ` Steen Hegelund
2020-11-30 14:54 ` Russell King - ARM Linux admin
2020-11-29 11:30 ` Russell King - ARM Linux admin
2020-11-30 14:30 ` Steen Hegelund
2020-11-30 14:50 ` Russell King - ARM Linux admin
2020-11-30 14:15 ` Steen Hegelund
2020-11-30 14:52 ` Russell King - ARM Linux admin
2020-11-30 14:10 ` Steen Hegelund
2020-11-28 19:24 ` Andrew Lunn
2020-12-01 11:11 ` Lars Povlsen
2020-11-29 17:16 ` Andrew Lunn
2020-11-30 13:33 ` Steen Hegelund
2020-11-29 17:26 ` Andrew Lunn
2020-11-30 13:31 ` Steen Hegelund
2020-11-29 17:35 ` Andrew Lunn
2020-11-30 14:42 ` Steen Hegelund
2020-11-27 13:33 ` [RFC PATCH 3/3] arm64: dts: sparx5: Add the Sparx5 switch node Steen Hegelund
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