Hello, thanks for the feedback and explanations.
>Not sure what you mean by that.
Your answer above says all I believe. The PHY must be capable of recognizing NTP packets. The question is: are there other HW mechanisms required from the PHY ? My guess again is no.
De : Miroslav Lichvar <mlichvar@xxxxxxxxxx>
Envoyé : lundi, juillet 13, 2026 10:30:26 AM
À : Pascal Regache <pascal@xxxxxxxxxxxxxx>
Cc : chrony-users@xxxxxxxxxxxxxxxxxxxx <chrony-users@xxxxxxxxxxxxxxxxxxxx>
Objet : Re: [chrony-users] Hardware time stamping and PHY specific features
On Fri, Jul 10, 2026 at 11:35:28PM +0200, Pascal Regache wrote:
> So my questions are:
> o Is there a detailed description somewhere on how it works down at the
> PHY level with NTP packets (I am a bit familiar with PTP engine in
> PHY) ?
For the only NTP-specific PHY I know (DP83640) there is this
description in the datasheet:
The DP83640 may be programmed to timestamp NTP packets instead of PTP
packets. This operation is enabled by setting the NTP_TS_EN control in
the PTP_TXCFG0 register. When configured for NTP timestamps, the
DP83640 will timestamp packets with the NTP UDP port number rather
than the PTP port number (note that the device cannot be configured to
timestamp both PTP and NTP packets).
The vast majority of HW that can timestamp NTP packets are doing that
in the MAC, not PHY, and it's providing timestamps for all packets
without inspecting them. Usually the timestamps are prepended to the
frames.
> o What are the minimum PHY set of features required for the mechanism
> to work ?
Not sure what you mean by that.
--
Miroslav Lichvar
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