Re: [PATCH net-next 3/7] idpf: support pacing offload

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Tony Nguyen wrote:
> 
> 
> On 7/6/2026 6:34 AM, Willem de Bruijn wrote:
> 
> ...
> > +static void idpf_tx_splitq_set_txtime(const struct idpf_tx_queue *tx_q,
> > +				      const struct sk_buff *skb,
> > +				      struct idpf_tx_splitq_params *tx_params)
> > +{
> > +	const int ts_gran_pow2 = 9;
> > +	u64 ts, now;
> > +
> > +	/* Skip if netpoll: not needed and not safe to call ktime helpers */
> > +	if (netpoll_tx_running(skb->dev))
> > +		return;
> > +
> > +	switch (skb->tstamp_type) {
> > +	case SKB_CLOCK_REALTIME:
> > +		ts = ktime_to_ns(ktime_add(skb->tstamp,
> > +					   ktime_mono_to_any(0, TK_OFFS_TAI) -
> > +					   ktime_mono_to_any(0, TK_OFFS_REAL)));
> > +		break;
> > +	case SKB_CLOCK_MONOTONIC:
> > +		ts = ktime_to_ns(ktime_mono_to_any(skb->tstamp, TK_OFFS_TAI));
> > +		break;
> > +	case SKB_CLOCK_TAI:
> > +		ts = ktime_to_ns(skb->tstamp);
> > +		break;
> > +	default:
> > +		WARN_ON_ONCE(1);
> > +		return;
> > +	}
> > +
> > +	now = ktime_get_clocktai_ns();
> > +	if (ts < now)
> > +		return;
> > +
> > +	/* beyond offload horizon? set overflow bit only */
> > +	if (ts > now + ((u64)skb->dev->pacing_offload_horizon * NSEC_PER_USEC)) {
> > +		tx_params->offload.desc_ts[2] = 1 << 7;
> > +		return;
> > +	}
> > +
> > +	ts >>= ts_gran_pow2;
> > +
> > +	tx_params->offload.desc_ts[0] = ts & 0xff;
> > +	tx_params->offload.desc_ts[1] = (ts >> 8) & 0xff;
> > +	tx_params->offload.desc_ts[2] = ((ts >> 16) & 0x7f);
> > +
> > +	/* 0 is valid 24b timestamp, but also means field unset.
> > +	 * Add 512 ns (ts_gran_pow2) to avoid this case
> > +	 */
> > +	if ((ts & 0x7fffff) == 0)
> > +		tx_params->offload.desc_ts[0] = 1;
> > +}
> 
> Slight nit but seems like this check can be moved before the assignments 
> (and then return) as we don't need to assign the other 2 bytes in this 
> situation?

Thanks for the reviews. I'll address this and Paolo's points in v2.