Re: [PATCH 2/2] net: ethernet: stmicro: stmmac: dwmac-rk: Add rv1126 support

[Andrew Lunn]

> > On Mon, Aug 29, 2022 at 06:50:42AM +0000, Anand Moon wrote:
> > > Rockchip RV1126 has GMAC 10/100/1000M ethernet controller
> > > via RGMII and RMII interfaces are configured via M0 and M1 pinmux.
> > >
> > > This patch adds rv1126 support by adding delay lines of M0 and M1
> > > simultaneously.
> >
> > What does 'delay lines' mean with respect to RGMII?
> >
> > The RGMII signals need a 2ns delay between the clock and the data
> > lines. There are three places this can happen:
> >
> > 1) In the PHY
> > 2) Extra long lines on the PCB
> > 3) In the MAC
> >
> > Generally, 1) is used, and controlled via phy-mode. A value of
> > PHY_INTERFACE_MODE_RGMII_ID passed to the PHY driver means it will add
> > these delays.
> >
> > You don't want both the MAC and the PHY adding delays.
> >
> These are set to enable MAC transmit clock delay set for Tx and Rx for
> iomux group.

Which does not answer my question. Is this the same as, or different
to, the 2ns delay required by RGMII?

    Andrew