Re: [PATCH net-next v3 0/5] net: stmmac: Add support for Allwinner A733 GMAC210

On mar. 29 sept. 2026 at 18:10, Andrew Lunn [off-list ref] wrote:

quoted

Thanks for the heads up. So if I'm reading the doc correctly the PHY
adds 2ns
 * on RX if there a 4.7k pull-up on RXD0
 * on TX if there a 4.7k pull-up on RXD1

The schematics for the board are available here [1]

* 4.7k pull-up on RXD0: so we should have 2ns Rx from the PHY
* 4.7k pull-down on RXD1: no idea what this does. Presumably no delay ?

I've cross-checked the HW, the resistors are actually fitted as the
schematic says they are.

With the HW setup, the MAC setup that works for me remains

	tx-internal-delay-ps = <1620>;
	rx-internal-delay-ps = <1800>;

These values suggests there are delays on both Rx an Tx.

I did not mean to suggest :)

To be clear, we have no control over the PHY delay.
The strapping/doc says the PHY provide 2ns on Rx, none on Tx (presumably)

But I must add 1.62ns on Tx and 1.8ns on Rx through the MAC for the link
to work properly (the values above).

I don't have an explanation for this. I assume the PHY actually adds no
delay, maybe the strapping implementation is broken. Maybe the PCB the
already adds a little delay which is why the MAC just need to add a
little less than 2ns.

quoted

I know it is not aligned with what it expected but still.

I'm flexible, if in the end this is what is required, that is fine. It
will need a comment explaining why it is needed, why the guidelines
are not being followed.

Where i have real problems is with developers who don't respect what
the guidelines say, even when their hardware could do what is
asked. They just do the minimum to make it work, and call it done.

The comment is then important, because i don't want developers using
this as an excuse not to do the correct thing.

Sure, no problem. I'll add a comment in DT when I'll submit it,
explaining what we have found regarding the PHY strapping and effects.

     Andrew

-- 
Jerome