Re: [PATCH net-next v1 1/1] net: phy: dp83td510: add cable testing support

From: Andrew Lunn
Date: Fri Jul 12 2024 - 11:20:39 EST


> > > +#define DP83TD510E_TDR_CFG2 0x301
> > > +#define DP83TD510E_TDR_END_TAP_INDEX_1 GENMASK(14, 8)
> > > +#define DP83TD510E_TDR_END_TAP_INDEX_1_DEF 36
> > > +#define DP83TD510E_TDR_START_TAP_INDEX_1 GENMASK(6, 0)
> > > +#define DP83TD510E_TDR_START_TAP_INDEX_1_DEF 3
> >
> > Does this correspond the minimum and maximum distance it will test?
> > Is this 3m to 36m?
>
> No. At least, i can't confirm it with tests.
>
> If I see it correctly, this PHY is using SSTDR instead of usual TDR.
> Instead of pulses it will send modulated transmission with default
> length of 16ms
>
> I tried my best google foo, but was not able to find anything
> understandable about "Start/End tap index for echo coeff sweep for segment 1"
> im context of SSTDR. If anyone know more about this, please tell me :)

I was just curious. Does not really matter with respect to getting the
patch applied.

Andrew