Date:   Thu, 4 Nov 2021 10:28:43 -0700
From:   Richard Cochran <richardcochran@gmail.com>
To:     Martin Kaistra <martin.kaistra@linutronix.de>
Cc:     Florian Fainelli <f.fainelli@gmail.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        John Stultz <john.stultz@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Stephen Boyd <sboyd@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH 4/7] net: dsa: b53: Add PHC clock support
Message-ID: <20211104172843.GA32548@hoboy.vegasvil.org>
References: <20211104133204.19757-1-martin.kaistra@linutronix.de>
 <20211104133204.19757-5-martin.kaistra@linutronix.de>
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On Thu, Nov 04, 2021 at 02:31:58PM +0100, Martin Kaistra wrote:

> +static void b53_ptp_overflow_check(struct work_struct *work)
> +{
> +	struct delayed_work *dw = to_delayed_work(work);
> +	struct b53_device *dev =
> +		container_of(dw, struct b53_device, overflow_work);
> +
> +	mutex_lock(&dev->ptp_mutex);
> +	timecounter_read(&dev->tc);
> +	mutex_unlock(&dev->ptp_mutex);
> +
> +	schedule_delayed_work(&dev->overflow_work, B53_PTP_OVERFLOW_PERIOD);
> +}
> +
> +int b53_ptp_init(struct b53_device *dev)
> +{
> +	mutex_init(&dev->ptp_mutex);
> +
> +	INIT_DELAYED_WORK(&dev->overflow_work, b53_ptp_overflow_check);

...

> @@ -97,4 +101,14 @@ struct b53_device {
>  	bool vlan_enabled;
>  	unsigned int num_ports;
>  	struct b53_port *ports;
> +
> +	/* PTP */
> +	bool broadsync_hd;
> +	struct ptp_clock *ptp_clock;
> +	struct ptp_clock_info ptp_clock_info;
> +	struct cyclecounter cc;
> +	struct timecounter tc;
> +	struct mutex ptp_mutex;
> +#define B53_PTP_OVERFLOW_PERIOD (HZ / 2)
> +	struct delayed_work overflow_work;

Instead of generic work, consider implementing
ptp_clock_info::do_aux_work instead.

The advantage is that you get a named kernel thread that can be given
scheduling priority administratively.

Thanks,
Richard