linux-kernel - Re: [PATCH net-next v2 1/1] net: stmmac: Add support for external trigger timestamping

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Date:   Fri, 9 Apr 2021 17:50:04 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Wong Vee Khee <vee.khee.wong@...ux.intel.com>
Cc:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S . Miller" <davem@...emloft.net>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Voon Weifeng <weifeng.voon@...el.com>,
        Ong Boon Leong <boon.leong.ong@...el.com>,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org,
        Richard Cochran <richardcochran@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 1/1] net: stmmac: Add support for external
 trigger timestamping

Other than the minor nit below LGTM. Let's give Richard one more day.

On Thu,  8 Apr 2021 01:04:42 +0800 Wong Vee Khee wrote:
> +static void timestamp_interrupt(struct stmmac_priv *priv)
> +{
> +	struct ptp_clock_event event;
> +	unsigned long flags;
> +	u32 num_snapshot;
> +	u32 ts_status;
> +	u32 tsync_int;
> +	u64 ptp_time;
> +	int i;
> +
> +	tsync_int = readl(priv->ioaddr + GMAC_INT_STATUS) & GMAC_INT_TSIE;
> +
> +	if (!tsync_int)
> +		return;
> +
> +	/* Read timestamp status to clear interrupt from either external
> +	 * timestamp or start/end of PPS.
> +	 */
> +	ts_status = readl(priv->ioaddr + GMAC_TIMESTAMP_STATUS);
> +
> +	if (priv->plat->ext_snapshot_en) {

Are you intending to add more code after this if? Otherwise you could
flip the condition and return early instead of having the extra level
of indentation.

> +		num_snapshot = (ts_status & GMAC_TIMESTAMP_ATSNS_MASK) >>
> +			       GMAC_TIMESTAMP_ATSNS_SHIFT;
> +
> +		for (i = 0; i < num_snapshot; i++) {
> +			spin_lock_irqsave(&priv->ptp_lock, flags);
> +			get_ptptime(priv->ptpaddr, &ptp_time);
> +			spin_unlock_irqrestore(&priv->ptp_lock, flags);
> +			event.type = PTP_CLOCK_EXTTS;
> +			event.index = 0;
> +			event.timestamp = ptp_time;
> +			ptp_clock_event(priv->ptp_clock, &event);
> +		}
> +	}
> +}

Not really related to this patch but how does stmmac set IRQF_SHARED
and yet not track if it indeed generated the interrupt? Isn't that
against the rules?