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

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Message-ID: <CO1PR11MB5089A5A5ED6C76AA479BE1F4D6122@CO1PR11MB5089.namprd11.prod.outlook.com>
Date: Wed, 8 Jan 2025 00:33:21 +0000
From: "Keller, Jacob E" <jacob.e.keller@...el.com>
To: Jiawen Wu <jiawenwu@...stnetic.com>, 'Richard Cochran'
	<richardcochran@...il.com>
CC: "andrew+netdev@...n.ch" <andrew+netdev@...n.ch>, "davem@...emloft.net"
	<davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"linux@...linux.org.uk" <linux@...linux.org.uk>, "horms@...nel.org"
	<horms@...nel.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"vadim.fedorenko@...ux.dev" <vadim.fedorenko@...ux.dev>,
	"mengyuanlou@...-swift.com" <mengyuanlou@...-swift.com>
Subject: RE: [PATCH net-next v2 3/4] net: wangxun: Implement do_aux_work of
 ptp_clock_info



> -----Original Message-----
> From: Jiawen Wu <jiawenwu@...stnetic.com>
> Sent: Monday, January 6, 2025 9:59 PM
> 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.

Thanks,
Jake

>