Re: [patch V2 00/25] timekeeping/ptp: Expand snapshot functionality

[Jacob Keller]

On 5/29/2026 12:59 PM, Thomas Gleixner wrote:
> This is an update to V1 which can be found here:
> 
>    https://lore.kernel.org/lkml/20260526165826.392227559@xxxxxxxxxx
> 
> PTP wants to grow new snapshot functionality, which provides not only the
> captured CLOCK* values, but also the underlying clocksource counter value.
> 
>    https://lore.kernel.org/20260515164033.6403-1-akiyano@xxxxxxxxxx
> 
> There was quite some discussion in seemingly related threads how to capture
> these values and how to provide core infrastructure so that driver writers
> have something to work with
> 
>    https://lore.kernel.org/20260514225842.110706-1-hramamurthy@xxxxxxxxxx
>    https://lore.kernel.org/20260520135207.37826-1-dwmw2@xxxxxxxxxxxxx
> 
> This series implements the timekeeping related mechanisms to:
> 
>      1) Capture CLOCK values along with the clocksource counter value for
>      	non-hardware based sampling
> 
>      2) Expanding the hardware cross time stamp mechanism to hand back the
>      	clocksource counter value, which was captured by the device, along
>      	with the related CLOCK values
> 
>      3) Adding AUX clock support to the hardware cross timestamping core
> 
>      4) Add support for derived clocksources to the snapshot mechanism (New
>      	in V2)
> 
> Changes vs. V1:
> 
>   - Fixed the ptp_ocp typo - 0-day, Jakub
> 
>   - Renamed the system_time_snapshot members sys and raw so systime and
>     monoraw to make them less ambigous.
> 
>   - Fixed the error case return values of get_device_system_crosststamp()
> 
>   - Made ktime_snapshot_id() void as there is no point for the return
>     value, which is nowhere checked and cannot be propagated.
>     system_time_snapshot::valid has to be evaluated at the call sites
>     anyway. - Jacob
> 
>   - Picked up the first patch from Davids follow up series, which extends
>     the snapshot mechanism so that derived clocksources (like kvmclock and
>     Hyper-V scaled TSC) can return the actual underlying hardware counter
>     value (TSC for the two examples).
> 
>   - Collected Reviewed/Acked/Tested-by tags
> 
> Delta patch against v1 below.
> 
> The series is based on v7.1-rc2 and also available from git:
> 
>     git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git timekeeping-ptp-extend-v2
> 
> Thanks,

The changes in v2 are great! Appreciate it.

Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>