On Fri, Aug 09, 2024 at 04:38:40PM -0700, Tristram.Ha@xxxxxxxxxxxxx wrote: > From: Tristram Ha <tristram.ha@xxxxxxxxxxxxx> > > The SGMII module of KSZ9477 switch can be setup in 3 ways: 0 for direct > connect, 1 for 1000BaseT SFP, and 2 for 10/100/1000 SFP. > > SFP is typically used so the default is 1. The driver can detect > 10/100/1000 SFP and change the mode to 2. For direct connect this mode > has to be explicitly set to 0 as driver cannot detect that > configuration. Is 1 actually 1000BaseX? An SFP module using fibre would typically want 1000BaseX, and only support one speed. An SFP module using copper typically has a PHY in it, it performs auto-neg on the media side, and then uses SGMII inband signalling to tell the MAC what data rate, symbol duplication to do. And maybe mode 0 has in-band signalling turned off, in which case 1000BaseX and SGMII become identical, because it is the signalling which is different. Andrew
