Re: [PATCH] net: macb: Fix ptp time adjustment for large negative delta

[Nicolas Ferre]

On 20/06/2018 at 13:34, Harini Katakam wrote:
> When delta passed to gem_ptp_adjtime is negative, the sign is
> maintained in the ns_to_timespec64 conversion. Hence timespec_add
> should be used directly. timespec_sub will just subtract the negative
> value thus increasing the time difference.
>
> Signed-off-by: Harini Katakam <harini.katakam@xxxxxxxxxx>

Makes sense:
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>

> ---
>   drivers/net/ethernet/cadence/macb_ptp.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/net/ethernet/cadence/macb_ptp.c b/drivers/net/ethernet/cadence/macb_ptp.c
> index 2220c77..6788351 100644
> --- a/drivers/net/ethernet/cadence/macb_ptp.c
> +++ b/drivers/net/ethernet/cadence/macb_ptp.c
> @@ -170,10 +170,7 @@ static int gem_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
>   
>   	if (delta > TSU_NSEC_MAX_VAL) {
>   		gem_tsu_get_time(&bp->ptp_clock_info, &now);
> -		if (sign)
> -			now = timespec64_sub(now, then);
> -		else
> -			now = timespec64_add(now, then);
> +		now = timespec64_add(now, then);
>   
>   		gem_tsu_set_time(&bp->ptp_clock_info,
>   				 (const struct timespec64 *)&now);


--
Nicolas Ferre