Subject: RE: [PATCH v3 net-next 3/3] net: ena: Add PHC documentation

From: "Arinzon, David" <[email-masked]>
Date: Tue, 5 Nov 2024 16:52:11 +0000

> >>> +=================
> >> ======================================================
> >>> +**phc_cnt**         Number of successful retrieved timestamps (below
> >> expire timeout).
> >>> +**phc_exp**         Number of expired retrieved timestamps (above
> >> expire timeout).
> >>> +**phc_skp**         Number of skipped get time attempts (during block
> >> period).
> >>> +**phc_err**         Number of failed get time attempts (entering into
> block
> >> state).
> >>> +=================
> >> ======================================================
> >>
> >> I seem to recall we had an unpleasant conversation about using
> >> standard stats recently. Please tell me where you looked to check if
> >> Linux has standard stats for packet timestamping. We need to add the
> right info there.
> >> --
> >> pw-bot: cr
> >
> > Hi Jakub,
> >
> > Just wanted to clarify that this feature and the associated
> > documentation are specifically intended for reading a HW timestamp, not
> for TX/RX packet timestamping.
> > We reviewed similar drivers that support HW timestamping via
> > `gettime64` and `gettimex64` APIs, and we couldn't identify any that
> capture or report statistics related to reading a HW timestamp.
> > Let us know if further details would be helpful.
> 
> David, did you consider Rahul's recent timestamping stats API?
> 0e9c127729be ("ethtool: add interface to read Tx hardware timestamping
> statistics")

Hi Gal,

We've looked into the `get_ts_stats` ethtool hook, and it refers to TX HW packet timestamping
and not HW timestamp which is retrieved through `gettime64` and `gettimex64`.