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

Hi Russell,

Thanks for your comments.

On Mon, 2021-06-07 at 10:15 +0100, Russell King (Oracle) wrote:

EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe

On Fri, Jun 04, 2021 at 10:55:53AM +0200, Steen Hegelund wrote:

quoted

+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.

OK.  I will assume speed is not known in this callback.

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

Yes that would be a very useful addition.
Should I add PHY_INTERFACE_MODE_25GBASER in this series or should that be added as a separate
series?

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.

The high speed interfaces (> 2.5G) do not support any in-band signalling, so the only way that e.g a
10G interface running at 2.5G will be able to link up with its partner is if both ends configure the
speed manually via ethtool.
	

quoted

+             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.

OK.

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

-- 
BR
Steen

-=-=-=-=-=-=-=-=-=-=-=-=-=-=
steen.hegelund@microchip.com