Re: [PATCH net-next v2] net: dsa: microchip: Add SGMII port support to KSZ9477 switch

On Fri, Jan 17, 2025 at 12:56:14AM +0000, Tristram.Ha@microchip.com wrote:

The KSZ9477 SGMII module does use DesignWare IP, but its implementation
is probably too old as some registers do not match.  When using XPCS
driver link detection works but the SGMII port does not pass traffic for
some SFPs.  It is probably doable to update the XPCS driver to work in
KSZ9477, but there is no way to submit that patch as that may affect
other hardware implementation.

One thing that is strange is that driver enables interrupt for 1000BaseX
mode but not SGMII mode, but in KSZ9477 SGMII mode can trigger link up
and link down interrupt but 1000BaseX can only trigger link up interrupt.

Sometimes, the "collaborative" aspect of open source projects does work
out, and you might get help, feedback and/or regression testing for
hardware you don't have. Sure, it doesn't always work out, but I suggest
you give it a try and not put the cart before the horses.