On Sun, Nov 29, 2020 at 10:52:45AM +0000, Russell King - ARM Linux admin wrote:
> 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.
(Sorry, I keep spotting bits in the code - it's really not an easy
chunk of code to review.)
I'm also not sure that this is really correct:
+ status->serdes_link = !phy_validate(port->serdes, PHY_MODE_ETHERNET,
+ port->conf.portmode, NULL);
The documentation for phy_validate() says:
* Used to check that the current set of parameters can be handled by
* the phy. Implementations are free to tune the parameters passed as
* arguments if needed by some implementation detail or
* constraints. It will not change any actual configuration of the
* PHY, so calling it as many times as deemed fit will have no side
* effect.
and clearly, passing NULL for opts, gives the function no opportunity
to do what it's intended, so phy_validate() is being used for some
other purpose than that which the drivers/phy subsystem intends it to
be used for.
--
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