Re: [Linuxptp-users] AM571x linuxptp support

[Richard C. <ric...@gm...>]

On Fri, Nov 18, 2016 at 08:20:22AM -0500, David Cemin wrote:
> thank you for your prompt response. I assume you have tried it on TI AM335x
> then. If that is the case, did you use any specific development kit ?

It works on the BBW and BBB.

> Im
> interested in understanding what kind of external hardware would be
> required for this (i.e. external controlled oscillator).

It works without external HW, but see below.

We don't have any generic kernel support for external VCOs, but you
can hack it in for a particular MAC by changing the PHC driver's
.adjfreq method to steer the VCO instead.

> Also, do you know
> anything about the 1pps output on these devices ?

The frequency adjustment logic on the am335x is broken.  The driver
implements frequency adjustment in SW.  So the HW functions are
useless.  Even if the HW frequency worked, still the resolution of the
capture/compare logic is so coarse as to be unusable, IIRC.

HTH,
Richard