RE: [net-next, v3, 02/10] ptp: support ptp physical/virtual clocks conversion

[Y.b. Lu]

Hi Richard,

> -----Original Message-----
> From: Y.b. Lu
> Sent: 2021年6月22日 18:35
> To: Richard Cochran <richardcochran@xxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> linux-kselftest@xxxxxxxxxxxxxxx; mptcp@xxxxxxxxxxxxxxx; David S . Miller
> <davem@xxxxxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Mat Martineau
> <mathew.j.martineau@xxxxxxxxxxxxxxx>; Matthieu Baerts
> <matthieu.baerts@xxxxxxxxxxxx>; Shuah Khan <shuah@xxxxxxxxxx>; Michal
> Kubecek <mkubecek@xxxxxxx>; Florian Fainelli <f.fainelli@xxxxxxxxx>;
> Andrew Lunn <andrew@xxxxxxx>; Rui Sousa <rui.sousa@xxxxxxx>; Sebastien
> Laveze <sebastien.laveze@xxxxxxx>
> Subject: RE: [net-next, v3, 02/10] ptp: support ptp physical/virtual clocks
> conversion
> 
> Hi Richard,
> 
> > -----Original Message-----
> > From: Richard Cochran <richardcochran@xxxxxxxxx>
> > Sent: 2021年6月18日 2:28
> > To: Y.b. Lu <yangbo.lu@xxxxxxx>
> > Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > linux-kselftest@xxxxxxxxxxxxxxx; mptcp@xxxxxxxxxxxxxxx; David S .
> > Miller <davem@xxxxxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Mat
> > Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>; Matthieu Baerts
> > <matthieu.baerts@xxxxxxxxxxxx>; Shuah Khan <shuah@xxxxxxxxxx>; Michal
> > Kubecek <mkubecek@xxxxxxx>; Florian Fainelli <f.fainelli@xxxxxxxxx>;
> > Andrew Lunn <andrew@xxxxxxx>; Rui Sousa <rui.sousa@xxxxxxx>;
> Sebastien
> > Laveze <sebastien.laveze@xxxxxxx>
> > Subject: Re: [net-next, v3, 02/10] ptp: support ptp physical/virtual
> > clocks conversion
> >
> > On Tue, Jun 15, 2021 at 05:45:09PM +0800, Yangbo Lu wrote:
> >
> > > diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
> > > index 3f388d63904c..6949afc9d733 100644
> > > --- a/drivers/ptp/ptp_private.h
> > > +++ b/drivers/ptp/ptp_private.h
> > > @@ -46,6 +46,9 @@ struct ptp_clock {
> > >  	const struct attribute_group *pin_attr_groups[2];
> > >  	struct kthread_worker *kworker;
> > >  	struct kthread_delayed_work aux_work;
> > > +	u8 n_vclocks;
> >
> > Hm, type is u8, but ...
> >
> > > +	struct mutex n_vclocks_mux; /* protect concurrent n_vclocks access */
> > > +	bool vclock_flag;
> > >  };
> > >
> >
> > >  #define info_to_vclock(d) container_of((d), struct ptp_vclock,
> > > info) diff --git a/include/uapi/linux/ptp_clock.h
> > > b/include/uapi/linux/ptp_clock.h index 1d108d597f66..4b933dc1b81b
> > > 100644
> > > --- a/include/uapi/linux/ptp_clock.h
> > > +++ b/include/uapi/linux/ptp_clock.h
> > > @@ -69,6 +69,11 @@
> > >   */
> > >  #define PTP_PEROUT_V1_VALID_FLAGS	(0)
> > >
> > > +/*
> > > + * Max number of PTP virtual clocks per PTP physical clock  */
> > > +#define PTP_MAX_VCLOCKS			20
> >
> > Only 20 clocks are allowed?  Why?
> 
> Initially I think vclock can be used for ptp multiple domains synchronization.
> Since the PTP domainValue is u8, u8 vclock number is large enough.
> This is not a good idea to hard-code a PTP_MAX_VCLOCKS value. But it looks a
> little crazy to create numbers of vclocks via one command (echo n >
> /sys/class/ptp/ptp0/n_vclocks).
> Maybe a typo creates hundreds of vclocks we don’t need.
> Do you think we should be care about setting a limitation of vclock number?
> Any suggestion for implementation?
> Thanks.

I sent v4. I removed the u8 limitation for vclocks number, using unsigned int instead.
I introduced max_vclocks attribute which could be re-configured.
Please help to review.
Thanks.

> 
> >
> > Thanks,
> > Richard