Re: [PATCH net-next v3 03/10] net: sparx5: add hostmode with phylink support

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Steen Hegelund <steen.hegelund@microchip.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Andrew Lunn <andrew@lunn.ch>,
	Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Madalin Bucur <madalin.bucur@oss.nxp.com>,
	Mark Einon <mark.einon@gmail.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Simon Horman <simon.horman@netronome.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Bjarni Jonasson <bjarni.jonasson@microchip.com>,
	Lars Povlsen <lars.povlsen@microchip.com>
Subject: Re: [PATCH net-next v3 03/10] net: sparx5: add hostmode with phylink support
Date: Mon, 7 Jun 2021 10:15:36 +0100	[thread overview]
Message-ID: <20210607091536.GA30436@shell.armlinux.org.uk> (raw)
In-Reply-To: <20210604085600.3014532-4-steen.hegelund@microchip.com>

On Fri, Jun 04, 2021 at 10:55:53AM +0200, Steen Hegelund 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;
> +
> +	conf = port->conf;
> +	conf.power_down = false;
> +	conf.portmode = state->interface;
> +	conf.speed = state->speed;
> +	conf.autoneg = state->an_enabled;
> +	conf.pause = state->pause;
> +
> +	if (state->interface == PHY_INTERFACE_MODE_10GBASER) {
> +		if (state->speed == SPEED_UNKNOWN) {
> +			/* When a SFP is plugged in we use capabilities to
> +			 * default to the highest supported speed
> +			 */
> +			if (phylink_test(state->advertising, 25000baseSR_Full) ||
> +			    phylink_test(state->advertising, 25000baseCR_Full))
> +				conf.speed = SPEED_25000;
> +			else if (state->interface == PHY_INTERFACE_MODE_10GBASER)
> +				conf.speed = SPEED_10000;
> +		} else if (state->speed == SPEED_2500) {
> +			conf.portmode = PHY_INTERFACE_MODE_2500BASEX;
> +		} else if (state->speed == SPEED_1000) {
> +			conf.portmode = PHY_INTERFACE_MODE_1000BASEX;
> +		}

1) As detailed in the documentation for phylink, state->speed is not
   guaranteed to be valid in the mac_config method.

2) We clearly need PHY_INTERFACE_MODE_25GBASER rather than working
   around this by testing bits in the advertising bitmap.

3) I really don't get what's going on with setting the port mode to
   2500base-X and 1000base-X here when state->interface is 10GBASER.

> +		if (phylink_test(state->advertising, FIBRE))
> +			conf.media = PHY_MEDIA_SR;
> +		else
> +			conf.media = PHY_MEDIA_DAC;
> +	}
> +
> +	if (!port_conf_has_changed(&port->conf, &conf))
> +		return;
> +}
> +
> +static void sparx5_phylink_mac_link_up(struct phylink_config *config,
> +				       struct phy_device *phy,
> +				       unsigned int mode,
> +				       phy_interface_t interface,
> +				       int speed, int duplex,
> +				       bool tx_pause, bool rx_pause)
> +{

This is the only place that the MAC is guaranteed to know the
negotiated speed.

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

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