On 18/01/2026 18:01, Andrew Lunn wrote:

On Sun, Jan 18, 2026 at 04:07:38PM +0200, Josua Mayer wrote:

quoted

The extended compliance code value SFF8024_ECC_100GBASE_ER4_25GBASE_ER
(0x3) means either 4-lane 100G or single lane 25G.

Is there a way to tell them apart?

The physical connectors are different, so we can know from the
device-tree compatible string.

For now sfp driver does not support qsfp.

If it is a QSFP, it means 4-lane 100G?

This is my suspicion, but I have not parsed real-world qsfp eeproms.

You can however split it into
4x 25GBASE_ER, if the MAC supports port spitting? If it is an SFP, it
must mean 25GBASE_ER because the SFP only supports a single lane?

Does it?
I thought SR, ER and LR indicate distance not host interface lane count.

Either way if you have a QSFP module, there is a single module with a single
eeprom on a single connector of 4 lanes.

When you have SFP module, there is a module / eeprom for each lane.

quoted

Set 25000baseLR_Full mode supported in addition to the already set
100000baseLR4_ER4_Full, and handle it in sfp_select_interface.

This fixes detection of 25G capability for two SFP fiber modules:

- GigaLight GSS-SPO250-LRT
- FS SFP-25G23-BX20-I

Are these SFPs or QSFPs?

SFP.

quoted

Signed-off-by: Josua Mayer <redacted>
---
  drivers/net/phy/sfp-bus.c | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/sfp-bus.c b/drivers/net/phy/sfp-bus.c
index b945d75966d5..2caa0e0c4ec8 100644
--- a/drivers/net/phy/sfp-bus.c
+++ b/drivers/net/phy/sfp-bus.c

@@ -247,6 +247,7 @@ static void sfp_module_parse_support(struct sfp_bus *bus,
  	case SFF8024_ECC_100GBASE_LR4_25GBASE_LR:
  	case SFF8024_ECC_100GBASE_ER4_25GBASE_ER:
  		phylink_set(modes, 100000baseLR4_ER4_Full);
+		phylink_set(modes, 25000baseLR_Full);

Given the question above, i'm wondering if it is as simple as this, or
we need to look at the type of SFP?

I don't think we need to worry about QSFP at this time.