Re: [PATCH net-next 1/3] ptp: Allow reassigning calibration pin function

On Thu, Jun 26, 2014 at 08:14:58AM +0200, Christian Riesch wrote:

On Thu, Jun 26, 2014 at 7:21 AM, Richard Cochran [off-list ref] wrote:

quoted

Reassigning the calibration function never makes sense, because it is
only used in the driver probe method.

Yes, indeed, but isn't that a bug? I think the calibration should be
done again whenever the clock is loaded with a new value, i.e. in
ptp_dp83640_settime. See section 3.1 in [1]: "All subsequent settings
should use a step
adjustment or temporary rate adjustment, which should occur at each
PHY without introducing any error." This means, whenever we do
something else (directly write to the clock register), we must
recalibrate.

When we write the time, we use the broadcast address, and so the PHYs
receive the data at exactly the same time on the MDIO bus. But maybe
they would still need a new, fine calibration. Can you test this?

(I don't have a board with two phys.)

Thanks,
Richard