Re: [PATCH net-next v3 1/2] ptp: introduce PTP_CLOCK_EXTOFF event for the measured external offset

[Richard Cochran <richardcochran@gmail.com>]

On Thu, Dec 14, 2023 at 09:59:32PM +0000, Min Li wrote:

> Would it be Ok if I use the flags to differentiate extts events from extoff?

That makes sense to me.  We can return the relevant
ptp_extts_request.flags.  Something like:

#define PTP_EXTTS_FLAGS_VALID	PTP_ENABLE_FEATURE

Then you can return

	ptp_extts_event.flags = PTP_EXTTS_FLAGS_VALID | PTP_EXT_OFFSET;

Later on, other drivers can indicate PTP_[RISING|FALLING]_EDGE, if
they can tell which one happened.

>  struct ptp_extts_event {
> -       struct ptp_clock_time t; /* Time event occured. */
> +       union {
> +               struct ptp_clock_time t; /* Time event occurred. */
> +               __s64 offset_ns;         /* Offset event occurred. */

BTW, please don't make a union here.  Instead just add text to the
comment of `struct ptp_clock_time t`.

The `struct ptp_clock_time t` can be a postive or a negative value
(see comment at the top of the file), and so you can put an offset in
there as well.

Thanks,
Richard