Re: [PATCH net-next] net: stmmac: ptp: switch to gettimex64() interface

[Nicolai Buchwitz]

Hi James

On 6.10.2026 12:36, James Clark wrote:
> The stmmac PTP support currently implements the gettime64 callback to
> retrieve the hardware clock time. Update the implementation to provide
> the gettimex64 callback instead, adding support for the
> PTP_SYS_OFFSET_EXTENDED ioctl.
>
> The system clock readings are taken around the read of the nanoseconds
> register in get_systime(), so get_systime() gains a 
> ptp_system_timestamp
> argument. rmb() is used to ensure proper ordering on weakly ordered
> architectures.
>
> Assisted-by: LLM
> Signed-off-by: James Clark <jjc@xxxxxxxxxx>
> ---
> Tested on a Radxa ZERO 3E (RK3566, DWMAC 4/5) running net-next.
> Width of the interval between the two system clock readings
> bracketing each PHC read (2000 calls of 25 samples each):
>
>                                          min      median
> Before patch (PTP_SYS_OFFSET):           875 ns   1167 ns
> After patch (PTP_SYS_OFFSET_EXTENDED):   291 ns    584 ns
>
> On this board the 24 MHz arch timer counter advances in steps of 7
> (~292 ns), so all intervals are multiples of that.

> [...]

(for the other patches you have prepared I will have a look later this 
week)

Reviewed-by: Nicolai Buchwitz <nb@xxxxxxxxxxx>

Thanks,
Nicolai