[Intel-wired-lan] [PATCH iwl-net v1 3/5] igc: Move ktime snapshot into PTM retry loop

[Corinna Vinschen]

On Aug  6 17:30, christopher.s.hall at intel.com wrote:
> From: Christopher S M Hall <christopher.s.hall at intel.com>
> 
> Move ktime_get_snapshot() into the loop. If a retry does occur, a more
> recent snapshot will result in a more accurate cross-timestamp.
> 
> Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
> Signed-off-by: Christopher S M Hall <christopher.s.hall at intel.com>
> ---
>  drivers/net/ethernet/intel/igc/igc_ptp.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
> index 00cc80d8d164..fb885fcaa97c 100644
> --- a/drivers/net/ethernet/intel/igc/igc_ptp.c
> +++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
> @@ -1011,16 +1011,16 @@ static int igc_phc_get_syncdevicetime(ktime_t *device,
>  	int err, count = 100;
>  	ktime_t t1, t2_curr;
>  
> -	/* Get a snapshot of system clocks to use as historic value. */
> -	ktime_get_snapshot(&adapter->snapshot);
> -
> +	/* Doing this in a loop because in the event of a
> +	 * badly timed (ha!) system clock adjustment, we may
> +	 * get PTM errors from the PCI root, but these errors
> +	 * are transitory. Repeating the process returns valid
> +	 * data eventually.
> +	 */
>  	do {
> -		/* Doing this in a loop because in the event of a
> -		 * badly timed (ha!) system clock adjustment, we may
> -		 * get PTM errors from the PCI root, but these errors
> -		 * are transitory. Repeating the process returns valid
> -		 * data eventually.
> -		 */
> +		/* Get a snapshot of system clocks to use as historic value. */
> +		ktime_get_snapshot(&adapter->snapshot);
> +
>  		igc_ptm_trigger(hw);
>  
>  		err = readx_poll_timeout(rd32, IGC_PTM_STAT, stat,
> -- 
> 2.34.1

Reviewed-by: Corinna Vinschen <vinschen at redhat.com>