> -----Original Message-----
> From: Richard Cochran [mailto:richardcoch...@gmail.com]
> Sent: Sunday, August 23, 2015 4:26 AM
> To: Thomas Gleixner
> Cc: Hall, Christopher S; Kirsher, Jeffrey T; h...@zytor.com;
> mi...@redhat.com; john.stu...@linaro.org; x...@kernel.org; linux-
> ker...@vger.kernel.org; netdev@vger.kernel.org; intel-wired-
> l...@lists.osuosl.org; pet...@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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