netdev - Re: [PATCH iwl-net 09/10] idpf: add support for Rx timestamping

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Message-ID: <67366352c2c5b_3379ce29475@willemb.c.googlers.com.notmuch>
Date: Thu, 14 Nov 2024 15:53:38 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Milena Olech <milena.olech@...el.com>, 
 intel-wired-lan@...ts.osuosl.org
Cc: netdev@...r.kernel.org, 
 anthony.l.nguyen@...el.com, 
 przemyslaw.kitszel@...el.com, 
 Milena Olech <milena.olech@...el.com>, 
 Alexander Lobakin <aleksander.lobakin@...el.com>
Subject: Re: [PATCH iwl-net 09/10] idpf: add support for Rx timestamping

Milena Olech wrote:
> Add Rx timestamp function when the Rx timestamp value is read directly
> from the Rx descriptor. Add supported Rx timestamp modes.
> 
> Reviewed-by: Alexander Lobakin <aleksander.lobakin@...el.com>
> Signed-off-by: Milena Olech <milena.olech@...el.com>
> ---
>  drivers/net/ethernet/intel/idpf/idpf_ptp.c  | 74 ++++++++++++++++++++-
>  drivers/net/ethernet/intel/idpf/idpf_txrx.c | 30 +++++++++
>  drivers/net/ethernet/intel/idpf/idpf_txrx.h |  7 +-
>  3 files changed, 109 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_ptp.c b/drivers/net/ethernet/intel/idpf/idpf_ptp.c
> index f34642d10768..f9f7613f2a6d 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_ptp.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_ptp.c
> @@ -317,12 +317,41 @@ static int idpf_ptp_gettimex64(struct ptp_clock_info *info,
>  	return 0;
>  }
>  
> +/**
> + * idpf_ptp_update_phctime_rxq_grp - Update the cached PHC time for a given Rx
> + *				     queue group.

Why does each receive group have a separate cached value?
They're all caches of the same device clock.

> + * @grp: receive queue group in which Rx timestamp is enabled
> + * @split: Indicates whether the queue model is split or single queue
> + * @systime: Cached system time
> + */
> +static void
> +idpf_ptp_update_phctime_rxq_grp(const struct idpf_rxq_group *grp, bool split,
> +				u64 systime)
> +{
> +	struct idpf_rx_queue *rxq;
> +	u16 i;
> +
> +	if (!split) {
> +		for (i = 0; i < grp->singleq.num_rxq; i++) {
> +			rxq = grp->singleq.rxqs[i];
> +			if (rxq)
> +				WRITE_ONCE(rxq->cached_phc_time, systime);
> +		}
> +	} else {
> +		for (i = 0; i < grp->splitq.num_rxq_sets; i++) {
> +			rxq = &grp->splitq.rxq_sets[i]->rxq;
> +			if (rxq)
> +				WRITE_ONCE(rxq->cached_phc_time, systime);
> +		}
> +	}
> +}
> +

> +/**
> + * idpf_ptp_set_rx_tstamp - Enable or disable Rx timestamping
> + * @vport: Virtual port structure
> + * @rx_filter: bool value for whether timestamps are enabled or disabled
> + */
> +static void idpf_ptp_set_rx_tstamp(struct idpf_vport *vport, int rx_filter)
> +{
> +	vport->tstamp_config.rx_filter = rx_filter;
> +
> +	if (rx_filter == HWTSTAMP_FILTER_NONE)
> +		return;

Should this clear the bit if it was previously set, instead of returning immediately?
> +
> +	for (u16 i = 0; i < vport->num_rxq_grp; i++) {
> +		struct idpf_rxq_group *grp = &vport->rxq_grps[i];
> +		u16 j;
> +
> +		if (idpf_is_queue_model_split(vport->rxq_model)) {
> +			for (j = 0; j < grp->singleq.num_rxq; j++)
> +				idpf_queue_set(PTP, grp->singleq.rxqs[j]);
> +		} else {
> +			for (j = 0; j < grp->splitq.num_rxq_sets; j++)
> +				idpf_queue_set(PTP,
> +					       &grp->splitq.rxq_sets[j]->rxq);
> +		}
> +	}
> +}

> +static void
> +idpf_rx_hwtstamp(const struct idpf_rx_queue *rxq,
> +		 const struct virtchnl2_rx_flex_desc_adv_nic_3 *rx_desc,
> +		 struct sk_buff *skb)
> +{
> +	u64 cached_time, ts_ns;
> +	u32 ts_high;
> +
> +	if (!(rx_desc->ts_low & VIRTCHNL2_RX_FLEX_TSTAMP_VALID))
> +		return;
> +
> +	cached_time = READ_ONCE(rxq->cached_phc_time);
> +
> +	ts_high = le32_to_cpu(rx_desc->ts_high);
> +	ts_ns = idpf_ptp_tstamp_extend_32b_to_64b(cached_time, ts_high);
> +
> +	*skb_hwtstamps(skb) = (struct skb_shared_hwtstamps) {
> +		.hwtstamp = ns_to_ktime(ts_ns),
> +	};

Simpler: skb_hwtstamps(skb)->hwtstamp = ns_to_ktime(ts_ns);