Re: [PATCH v4 net-next 0/7] ptp: Add PHC timestamp quality attributes

On Sun, 2026-07-26 at 18:41 -0700, Richard Cochran wrote:

On Tue, Jul 14, 2026 at 02:03:01AM +0000, Arthur Kiyanovski wrote:

quoted

This series adds quality attributes to PTP Hardware Clock (PHC)
timestamps, allowing userspace to obtain error bound, clock status,
timescale, and system counter values alongside timestamps in a
single
call.

Motivation
----------
The existing PTP APIs return timestamps without any indication of
their quality. Applications that need clock accuracy and
synchronization status commonly rely on external tools such as
ptp4l, which implement synchronization logic and can export their
measurement of clock accuracy.

Yes, and what is wrong with that?  Nothing, AFAICT

Sure, there's nothing wrong with that when it's userspace which is
actually doing the discipline of the clock.

This is for the cases where the device itself is responsible for the
discipline, and the driver is merely transporting the clock status.

? For managed PHC devices — such as

quoted

the ENA network adapter, whose clock is synchronized by the device
without userspace involvement — these tools are not available, and
the existing APIs lack a way to report quality metrics to consumers
of time.

So make some user space tool that advertises your device's qualities.

I suppose we could invent different device-specific ways for each of
the drivers to expose the same information? But let's not.