Re: [EXT] Re: [PATCH v2 RFC net-next 08/18] net: mvpp2: add FCA periodic timer configurations

Andrew Lunn
2021-01-24T19:12:28Z

On Sun, Jan 24, 2021 at 02:43:30PM +0000, Stefan Chulski wrote:
> >
> > ----------------------------------------------------------------------
> > On Sun, Jan 24, 2021 at 01:43:57PM +0200, stefanc@marvell.com wrote:
> > > +/* Set Flow Control timer x140 faster than pause quanta to ensure
> > > +that link
> > > + * partner won't send taffic if port in XOFF mode.
> >
> > Can you explain more why 140 times faster is desirable here? Why 140 times
> > and not, say, 10 times faster? Where does this figure come from, and what is
> > the reasoning? Is there a switch that requires it?
>
> I tested with 140.
> Actually regarding to spec each quanta should be equal to 512 bit times.
> In 10G bit time is 0.1ns.

And if the link has been negotiated to 10Mbps? Or is the clock already
scaled to the link speed?

Andrew