Messages in this thread | | | From | "Hall, Christopher S" <> | Subject | RE: [PATCH v3 3/4] Add support for driver cross-timestamp to PTP_SYS_OFFSET ioctl | Date | Mon, 24 Aug 2015 20:16:51 +0000 |
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> -----Original Message----- > From: Richard Cochran [mailto:richardcochran@gmail.com] > Sent: Sunday, August 23, 2015 4:26 AM > To: Thomas Gleixner > Cc: Hall, Christopher S; Kirsher, Jeffrey T; hpa@zytor.com; > mingo@redhat.com; john.stultz@linaro.org; x86@kernel.org; linux- > kernel@vger.kernel.org; netdev@vger.kernel.org; intel-wired- > lan@lists.osuosl.org; peterz@infradead.org > Subject: Re: [PATCH v3 3/4] Add support for driver cross-timestamp to > PTP_SYS_OFFSET ioctl > > On Sun, Aug 23, 2015 at 10:15:00AM +0200, Thomas Gleixner wrote: > > So why can't you take N samples from the synced hardware? It does not > > make any sense to me to switch to the imprecise mode if nsamples > 1. > > Ok, then I prefer to leave this "imprecise" method in place and ... > > > You can also provide a new IOCTL PTP_SYS_OFFSET_PRECISE which returns > > -ENOSYS if hardware timestamping is not available and avoid the whole > > nsamples dance for the case where we can get precise timestamps. > > have this for the new way. > > By keeping the imprecise method, we will be able to run both methods > on the new hardware. That will help to quantify how imprecise the old > method is.
This means: remove code changes from the PTP_SYS_OFFSET ioctl and call getsynctime64() from a new ioctl PTP_SYS_OFFSET_PRECISE. Right?
And use the same type (struct ptp_sys_offset) for the new ioctl? Or should a new simplified struct be used? Such as:
struct precise_ptp_sys_offset { struct ptp_clock_time device; struct ptp_clock_time system; };
Does it make sense to keep the "cross-timestamp" capabilities flag as-is?
> > Thanks, > Richard
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