Messages in this thread | | | From | Mahesh Bandewar (महेश बंडेवार) <> | Date | Wed, 8 May 2024 19:48:12 -0700 | Subject | Re: [PATCHv4 net-next] ptp/ioctl: support MONOTONIC_RAW timestamps for PTP_SYS_OFFSET_EXTENDED |
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On Tue, May 7, 2024 at 9:44 PM Richard Cochran <richardcochran@gmail.com> wrote: > > On Thu, May 02, 2024 at 02:10:47PM -0700, Mahesh Bandewar wrote: > > > @@ -457,14 +459,34 @@ static inline ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, > > > > static inline void ptp_read_system_prets(struct ptp_system_timestamp *sts) > > { > > - if (sts) > > - ktime_get_real_ts64(&sts->pre_ts); > > + if (sts) { > > + switch (sts->clockid) { > > + case CLOCK_REALTIME: > > + ktime_get_real_ts64(&sts->pre_ts); > > + break; > > + case CLOCK_MONOTONIC_RAW: > > + ktime_get_raw_ts64(&sts->pre_ts); > > + break; > > Why not add CLOCK_MONOTONIC as well? > That would be useful in many cases. > In fact my original implementation had it but my use case is really CLOCK_MONOTONIC_RAW, however, the general opinion on the thread was to implement what is needed now and if someone needs (CLOCK_MONOTONIC), it can be added at that time. So I removed it.
> > +/* > > + * ptp_sys_offset_extended - data structure for IOCTL operation > > + * PTP_SYS_OFFSET_EXTENDED > > + * > > + * @n_samples: Desired number of measurements. > > + * @clockid: clockid of a clock-base used for pre/post timestamps. > > + * @rsv: Reserved for future use. > > + * @ts: Array of samples in the form [pre-TS, PHC, post-TS]. The > > + * kernel provides @n_samples. > > + * > > + * History: > > + * v1: Initial implementation. > > + * > > + * v2: Use the first word of the reserved-field for @clockid. That's > > + * backward compatible since v1 expects all three reserved words > > + * (@rsv[3]) to be 0 while the clockid (first word in v2) for > > + * CLOCK_REALTIME is '0'. > > This is not really appropriate for a source code comment. The > un-merged patch series iterations are preserved at lore.kernel in case > someone needs that. > This was added in rev3 (Also this is the API version-history which intends to track how the fields have changed / morphed and not to be confused with the patch versions)
> The "backward compatible" information really wants to be in the commit > message. > I have the last paragraph in the commit log about compatibility.
Thanks for the comments, --mahesh..
> Thanks, > Richard >
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