On Wed, Mar 11, 2026 at 01:32:09PM +0100, Andrew Lunn wrote:

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With a SERDES component, the mapping becomes cleaner:
  component  name         supported
  MAC        mac          near-end
  SERDES     serdes-ned   near-end
  SERDES     serdes-nea   near-end
  SERDES     serdes-fed   far-end

If Linux where to drive the SERDES, what part of Linux would it be?
Generic PHY? How does your SERDES hardware block fit into 802.3? Which
clause describes it?

Hi Andrew,

On OcteonTx2 SoC, the SerDes (GSERM) is a HW block integrated into the
SoC die. It is not on an MDIO bus or any bus that Linux can enumerate.
The block is fully managed by the firmware running on the SoC. The NIC
driver configures it indirectly through firmware mailbox commands.

The data path looks like:
  MAC (RPM) --- SerDes (GSERM) --- module/PHY

In 802.3 terms, the closest match would be PMA. The GSERM handles
serialization/deserialization and the analog front-end.

A Linux Generic PHY is probably also PMA.

802.3 says very little about SERDES, it is not a well defined term. So
i think we want PCS and PMA, not SERDES as a loopback point.

That's a good point. I'm wondeirng whether to change "serdes" /
"SerDes" in my stmmac patches to be "pma".

-- 
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