Re: [PATCH net-next 3/3] net: stmmac: Add glue layer for Spacemit K3 SoC

Inochi Amaoto
2026-01-21T01:38:07Z

On Wed, Jan 21, 2026 at 02:29:23AM +0100, Andrew Lunn wrote:
> On Wed, Jan 21, 2026 at 06:36:01AM +0800, Inochi Amaoto wrote:
> > On Tue, Jan 20, 2026 at 02:56:26PM +0100, Andrew Lunn wrote:
> > > > +/* Note: the delay step value is at 0.1ps */
> > > > +static const unsigned int k3_delay_step_10x[4] = {
> > > > + 367, 493, 559, 685
> > > > +};
> > >
> > > Am i reading it correctly that RGMII delays are limited to these four
> > > values?
> > >
> > > If so, please add this list to the DT binding.
> > >
> >
> > No, these value are just adjustment interval, and it is also
> > controlled by another code register, the final delay is calculated
> > by the following formula:
> >
> > delay = delay_step * delay_code * 0.9;
> >
> > So the delay configuration needs to be calculated instead of
> > directly assigned.
>
> O.K.
>
> So what is the actual range? Can is do 1000ps? 2000ps? 3000ps? Should
> there be a basic range check to avoid dumb typos?

It can have a pretty big ranges, and I was told the total delay is fine
to work between [1200, 2800]. I guess it is fine for us to check the
upper limit?

Regards,
Inochi