[Linuxptp-devel] Question about adjust frequency

[Nithin N. S. <ns...@br...>]

Hi Richard,
I am trying to test the tg3 hardware ptp feature using ptp4l for driver patches that I will soon 
submit upstream.

I get an error that clock is not adjustable.

./ptp4l -i p6p4 -A -s -v
ptp4l[862288.218]: selected /dev/ptp5 as PTP clock
ptp4l[862288.218]: clock is not adjustable
failed to create a clock

I traced it to max_adj being set to 0 when we register ptp_caps in the driver.

The tg3 driver implements adjtime but not adjfreq. Is adjust frequency a mandatory requirement for 
ptp4l? If so why? Why do we need both adjust time and frequency? The hardware has a 1ns granularity 
counter and I don't get why this frequency tuning option is needed.

Sorry for my limited understanding. I inherited this code and don't know if something is missing.

Thanks,
Nithin.