[PATCH RFC net] net: dsa: mv88e6xxx: allow use of PHYs on CPU and DSA ports
From: Russell King (Oracle) <hidden>
Date: 2021-12-07 10:59:24
Martyn Welch reports that his CPU port is unable to link where it has been necessary to use one of the switch ports with an internal PHY for the CPU port. The reason behind this is the port control register is left forcing the link down, preventing traffic flow. This occurs because during initialisation, phylink expects the link to be down, and DSA forces the link down by synthesising a call to the DSA drivers phylink_mac_link_down() method, but we don't touch the forced-link state when we later reconfigure the port. Resolve this by also unforcing the link state when we are operating in PHY mode and the PPU is set to poll the PHY to retrieve link status information. Reported-by: Martyn Welch <redacted> Signed-off-by: Russell King (Oracle) <redacted> --- This patch requires: https://lore.kernel.org/r/E1muXm7-00EwJB-7n@rmk-PC.armlinux.org.uk If we convert Marvell DSA filly to split PCS (we have 6185 and 6352 complete, 6390 and 6393 remain), the "legacy_march2020" patches, and the phylink get_caps patches, we can then make Marvell DSA a non- legacy phylink driver. This gives much cleaner semantics concerning when the phylink_mac_config() method is called. Specifically, being non-legacy means phylink_mac_config() will no longer be called just before every phylink_mac_link_up() method call, and will not be called for in-band advertisement changes. This means that phylink_mac_config() will only be called when the port needs to be reconfigured, which allows drivers to force the link down for safe reconfiguration without potentially causing an infinite loop of link-down link-up events that can occur with the legacy behaviour. Thus, being non-legacy and allowing the forcing removes the need for DSA to synthesise a call to phylink_mac_link_down() at initialisation time for this driver... but we need all DSA drivers to be non-legacy before we can safely remove that. drivers/net/dsa/mv88e6xxx/chip.c | 56 +++++++++++++++++++------------- 1 file changed, 34 insertions(+), 22 deletions(-)
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 9f675464efc3..b033e653d3f4 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c@@ -698,7 +698,7 @@ static void mv88e6xxx_mac_config(struct dsa_switch *ds, int port, { struct mv88e6xxx_chip *chip = ds->priv; struct mv88e6xxx_port *p; - int err; + int err = 0; p = &chip->ports[port];
@@ -711,31 +711,43 @@ static void mv88e6xxx_mac_config(struct dsa_switch *ds, int port, return; mv88e6xxx_reg_lock(chip); - /* In inband mode, the link may come up at any time while the link - * is not forced down. Force the link down while we reconfigure the - * interface mode. - */ - if (mode == MLO_AN_INBAND && p->interface != state->interface && - chip->info->ops->port_set_link) - chip->info->ops->port_set_link(chip, port, LINK_FORCED_DOWN); - err = mv88e6xxx_port_config_interface(chip, port, state->interface); - if (err && err != -EOPNOTSUPP) - goto err_unlock; - - err = mv88e6xxx_serdes_pcs_config(chip, port, mode, state->interface, - state->advertising); - /* FIXME: we should restart negotiation if something changed - which - * is something we get if we convert to using phylinks PCS operations. - */ - if (err > 0) - err = 0; + if (mode != MLO_AN_PHY || !mv88e6xxx_phy_is_internal(ds, port)) { + /* In inband mode, the link may come up at any time while the + * link is not forced down. Force the link down while we + * reconfigure the interface mode. + */ + if (mode == MLO_AN_INBAND && + p->interface != state->interface && + chip->info->ops->port_set_link) + chip->info->ops->port_set_link(chip, port, + LINK_FORCED_DOWN); + + err = mv88e6xxx_port_config_interface(chip, port, + state->interface); + if (err && err != -EOPNOTSUPP) + goto err_unlock; + + err = mv88e6xxx_serdes_pcs_config(chip, port, mode, + state->interface, + state->advertising); + /* FIXME: we should restart negotiation if something changed - + * which is something we get if we convert to using phylinks + * PCS operations. + */ + if (err > 0) + err = 0; + } /* Undo the forced down state above after completing configuration - * irrespective of its state on entry, which allows the link to come up. + * irrespective of its state on entry, which allows the link to come + * up in the in-band case where there is no separate SERDES. Also + * ensure that the link can come up if the PPU is in use and we are + * in PHY mode (we treat the PPU as an effective in-band mechanism.) */ - if (mode == MLO_AN_INBAND && p->interface != state->interface && - chip->info->ops->port_set_link) + if (chip->info->ops->port_set_link && + ((mode == MLO_AN_INBAND && p->interface != state->interface) || + (mode == MLO_AN_PHY && mv88e6xxx_port_ppu_updates(chip, port)))) chip->info->ops->port_set_link(chip, port, LINK_UNFORCED); p->interface = state->interface;
--
2.30.2