Re: [Linuxptp-users] sanity_freq_limit

[Miroslav L. <mli...@re...>]

On Thu, Jun 18, 2015 at 01:58:13AM +0000, Daniel Le wrote:
> Additionally, in slave clock operation and software time stamping mode, how (and where in the code) ptp4l can be forced to step the system clock with the time it first receives from a grandmaster clock?

ptp4l should do that by default, it's set by the first_step_threshold
option.

> I have a couple of questions about the frequency limit. How much may it be reasonably increased from the default of 200000000 (20%)? And this parameter is only configurable via the config file. Is that correct?

Why do you need to increase it? 20% is a safe value for SW
timestamping. If you see clockcheck warning messages, it's probably a
bug in the kernel/driver. With HW timestamping a limit of a few
hundreds of ppm should be enough to cover the frequency offset between
a typical system clock and PTP clock.

-- 
Miroslav Lichvar