Re: [PATCH 4/7] net: dsa: b53: Add PHC clock support

[Richard Cochran]

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