Re: [PATCH net] ptp: netc: explicitly clear TMR_OFF during initialization

[Vadim Fedorenko <vadim.fedorenko@linux.dev>]

On 06/07/2026 09:12, wei.fang@oss.nxp.com wrote:
> From: Clark Wang <xiaoning.wang@nxp.com>
> 
> The NETC timer does not support function level reset, so TMR_OFF_L/H
> registers are not cleared by pcie_flr(). If TMR_OFF was set to a
> non-zero value in a previous binding, it will persist across driver
> rebind and cause inaccurate PTP time.
> 
> There is also a hardware issue: after a warm reset or soft reset,
> TMR_OFF_L/H registers appear to be cleared to zero, but the timer clock
> domain internally retains the stale value. When the timer is re-enabled,
> TMR_CUR_TIME continues to track the old offset until TMR_OFF is written
> explicitly. This can cause incorrect PTP timestamps and even PTP clock
> synchronization failures.
> 
> Per the recommendation from the IP team, explicitly write 0 to TMR_OFF
> in netc_timer_init() to flush the internally cached value and ensure
> TMR_CUR_TIME follows the freshly initialized counter.
> 
> Fixes: 87a201d59963 ("ptp: netc: add NETC V4 Timer PTP driver support")
> Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
> Signed-off-by: Wei Fang <wei.fang@nxp.com>
> ---
>   drivers/ptp/ptp_netc.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/ptp/ptp_netc.c b/drivers/ptp/ptp_netc.c
> index 94e952ee6990..5e381c354d74 100644
> --- a/drivers/ptp/ptp_netc.c
> +++ b/drivers/ptp/ptp_netc.c
> @@ -779,6 +779,7 @@ static void netc_timer_init(struct netc_timer *priv)
>   	netc_timer_wr(priv, NETC_TMR_FIPER_CTRL, fiper_ctrl);
>   	netc_timer_wr(priv, NETC_TMR_ECTRL, NETC_TMR_DEFAULT_ETTF_THR);
>   
> +	netc_timer_offset_write(priv, 0);
>   	ktime_get_real_ts64(&now);
>   	ns = timespec64_to_ns(&now);
>   	netc_timer_cnt_write(priv, ns);

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>