回覆: [net-next 2/4] ARM: dts: ast2600-evb: add default RGMII delay

[Jacky Chou <jacky_chou@xxxxxxxxxxxxxx>]

Hi Andrew,

Thank you for your reply.

> >  	phy-mode = "rgmii";
> >  	phy-handle = <&ethphy2>;
> >
> > +	tx-internal-delay-ps = <8>;
> > +	rx-internal-delay-ps = <4>;
> > +
> 
> Ideally you want:
> 
> 	phy-mode = "rgmii-id";
> 	tx-internal-delay-ps = <0>;
> 	rx-internal-delay-ps = <0>;
> 
> Since 'rgmii-id' correctly describes the hardware.

I still confuse about ethernet-controller.yaml.
It lists 'rgmi', 'rgmii-rxid', 'rgmii-txid' and 'rgmii-id'.

ethernet-controller.yaml
...
      # RX and TX delays are added by the MAC when required
      - rgmii

      # RGMII with internal RX and TX delays provided by the PHY,
      # the MAC should not add the RX or TX delays in this case
      - rgmii-id

      # RGMII with internal RX delay provided by the PHY, the MAC
      # should not add an RX delay in this case
      - rgmii-rxid

      # RGMII with internal TX delay provided by the PHY, the MAC
      # should not add an TX delay in this case
      - rgmii-txid
...

It seems if MAC has ability to add delay in MAC internal, driver can use these
values to describes the hardware design.

I know this topic had been discussed. I thought for a while to find a solution, but I 
cannot still understand why 'rgmii-id' is correct for HW?

Thanks,
Jacky