[PATCH net-next 04/14] net: stmmac: add infrastructure for hwifs to provide PCS

[Andrew Halaney]

On Fri, Aug 02, 2024 at 11:46:46AM GMT, Russell King (Oracle) wrote:
> Allow hwifs to provide a phylink_select_pcs() implementation via struct
> stmmac_ops, which can be used to provide a phylink PCS.
> 
> Code analysis shows that when STMMAC_FLAG_HAS_INTEGRATED_PCS is set,
> then:
> 
> 	stmmac_common_interrupt()
> 	stmmac_ethtool_set_link_ksettings()
> 	stmmac_ethtool_get_link_ksettings()
> 
> will all ignore the presence of the PCS. The latter two will pass the
> ethtool commands to phylink. The former will avoid manipulating the
> netif carrier state behind phylink's back based on the PCS status.
> 
> This flag is only set by the ethqos driver. From what I can tell,
> amongst the current kernel DT files that use the ethqos driver, only
> sa8775p-ride.dts enables ethernet, and this defines a SGMII-mode link
> to its PHYs without the "managed" property. Thus, phylink will be
> operating in MLO_AN_PHY mode, and inband mode will not be used.

"only sa8775p-ride.dts enables ethernet" is making this paragraph
confuse me a bit. I think you mean that only sa8775p-ride.dts is the
only device that is upstream and would use the flag?

There's a few other Qualcomm platforms that use the driver, but none of
them are SGMII (and none of them use the flag mentioned).

Otherwise I think this looks good to me.

Thanks,
Andrew