netdev - RE: [PATCH net-next v2 3/4] net: wangxun: Implement do_aux_work of ptp_clock

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Message-ID: <03e001db6196$82ad8480$88088d80$@trustnetic.com>
Date: Wed, 8 Jan 2025 14:28:20 +0800
From: Jiawen Wu <jiawenwu@...stnetic.com>
To: "'Keller, Jacob E'" <jacob.e.keller@...el.com>,
	"'Richard Cochran'" <richardcochran@...il.com>
Cc: <andrew+netdev@...n.ch>,
	<davem@...emloft.net>,
	<edumazet@...gle.com>,
	<kuba@...nel.org>,
	<pabeni@...hat.com>,
	<linux@...linux.org.uk>,
	<horms@...nel.org>,
	<netdev@...r.kernel.org>,
	<vadim.fedorenko@...ux.dev>,
	<mengyuanlou@...-swift.com>
Subject: RE: [PATCH net-next v2 3/4] net: wangxun: Implement do_aux_work of ptp_clock_info

> > > > > > +static int wx_ptp_feature_enable(struct ptp_clock_info *ptp,
> > > > > > +				 struct ptp_clock_request *rq, int on)
> > > > > > +{
> > > > > > +	struct wx *wx = container_of(ptp, struct wx, ptp_caps);
> > > > > > +
> > > > > > +	/**
> > > > > > +	 * When PPS is enabled, unmask the interrupt for the ClockOut
> > > > > > +	 * feature, so that the interrupt handler can send the PPS
> > > > > > +	 * event when the clock SDP triggers. Clear mask when PPS is
> > > > > > +	 * disabled
> > > > > > +	 */
> > > > > > +	if (rq->type != PTP_CLK_REQ_PPS || !wx->ptp_setup_sdp)
> > > > > > +		return -EOPNOTSUPP;
> > > > >
> > > > > NAK.
> > > > >
> > > > > The logic that you added in patch #4 is a periodic output signal, so
> > > > > your driver will support PTP_CLK_REQ_PEROUT and not PTP_CLK_REQ_PPS.
> > > > >
> > > > > Please change the driver to use that instead.
> > > > >
> > > > > Thanks,
> > > > > Richard
> > > >
> > > > This is a common misconception because the industry lingo uses PPS to mean
> > > > periodic output. I wonder if there's a place we can put an obvious warning
> > > > about checking if you meant PEROUT... I've had this issue pop up with
> > > > colleagues many times.
> > >
> > > Does a periodic output signal mean that a signal is output every second,
> > > whenever the start time is? But I want to implement that a signal is
> > > output when an integer number of seconds for the clock time.
> > >
> >
> > The periodic output can be configured in a bunch of ways, including periods that
> > are not a full second, when the signal should start, as well as in "one shot" mode
> > where it will only trigger once. You should check the possible flags in
> > <uapi/linux/ptp_clock.h> for the various options.
> 
> Looks like I need to configure perout.phase {0, 0} to output signal at the closest next
> second. And configure perout.period {0, 120 * 1000000} to keep the signal 120ms.
> 
> But where should I put these configuration? It used to be:
> 
> echo 1 > /sys/class/ptp/ptp0/pps_enable

I see. Thanks for your suggestion.