When I set port 9 on an mv88e6390, a cpu facing port to use 1000base-x (it also supports 2500base-x) in device-tree I find that phylink_helper_basex_speed() changes interface to PHY_INTERFACE_MODE_2500BASEX. The Ethernet adapter connecting to this switch port doesn't support 2500BASEX so it never establishes a link. If I hack up the code to force PHY_INTERFACE_MODE_1000BASEX it works fine.
state->an_enabled is true when phylink_helper_basex_speed() is called even when configured with fixed-link. This causes it to change the interface to PHY_INTERFACE_MODE_2500BASEX if 2500BaseX_Full is in state->advertising which it always is on the first call because phylink_create calls bitmap_fill(pl->supported, __ETHTOOL_LINK_MODE_MASK_NBITS) beforehand. Should state->an_enabled be true with MLO_AN_FIXED? I've also noticed that phylink_validate (which ends up calling phylink_helper_basex_speed) is called before phylink_parse_mode in phylink_create. If phylink_helper_basex_speed changes the interface mode this influences whether phylink_parse_mode (for MLO_AN_INBAND) sets 1000baseX_Full or 2500baseX_Full in pl->supported (which is then copied to pl->advertising). phylink_helper_basex_speed is then called again (via phylink_validate) which uses advertising to decide how to set interface. This seems like circular logic. To make matters even more confusing I see that mv88e6xxx_serdes_dcs_get_state uses state->interface to decide whether to set state->speed to SPEED_1000 or SPEED_2500. I've been thinking through how to get the desired behavior but I'm not even sure what the desired behavior is. If you set phy-mode to "1000base-x" in device-tree do you ever want interface to be set to PHY_INTERFACE_MODE_2500BASEX? If so just for MLO_AN_INBAND or also for ML_AN_FIXED? Do we want phylink_validate called in phylink_create even though it gets called anyway for MLO_AN_INBAND and ML_AN_FIXED later? Regards, George McCollister
