Re: [PATCH] net: sfp: add quirks for GPON ONT SFP sticks

[Daniel Golle]

On Mon, Apr 06, 2026 at 11:44:05AM +0000, John Pavlick wrote:
> Several GPON ONT SFP sticks based on Realtek RTL960x report
> 1000BASE-LX at 1300MBd in their EEPROM but can operate at 2500base-X.
> On hosts with serdes fixed at 2.5Gbase-X (e.g. Banana Pi R3 / MT7986),
> the kernel rejects them with 'no common interface modes'.

While the quirks themselves may be correct, the statement above is wrong.
The BananaPi R3 (and all MediaTek router SoCs) *do* support also
1000Base-X and SGMII, the SerDes is *not* "fixed at 2.5GBase-X". This
can easily be verified by plugging a random 1Gbps SFP module into the
board (eg. ubiquitous copper modules based on Marvell 88E1111 PHY).

Also you have to make sure to not break support for those modules on
boards which do not support 2500Base-X and need the module to operate
at 1000Base-X (eg. older MikroTik QCA9xxx-based MIPS boards).