Re: [PATCH 1/1] net: fec: ptp: avoid register access when ipg clock is disabled

Hi Richard,

Am Di., 23. Feb. 2021 um 15:27 Uhr schrieb Richard Cochran
[off-list ref]:

On Tue, Feb 23, 2021 at 09:00:32AM +0100, Heiko Thiery wrote:

quoted

HI Jakub,

Am Di., 23. Feb. 2021 um 04:00 Uhr schrieb Jakub Kicinski [off-list ref]:

quoted

Why is the PTP interface registered when it can't be accessed?

Perhaps the driver should unregister the PTP clock when it's brought
down?

I don't see any reason why a clock should stop ticking just because
the interface is down.  This is a poor driver design, but sadly it
gets copied and even defended.

It is not only the PHC clock that stops. Rather, it is the entire
ethernet building block in the SOC that is disabled, including the
PHC.

quoted

Good question, but I do not know what happens e.g. with linuxptp when
the device that was opened before will be gone.

If a network interface goes down, ptp4l will notice via rtnl and close
the interface.  Then it re-opens the sockets on rtnl up.  However, the
file descriptor representing the dynamic posix clock stays opened.

Thanks,

-- 
Heiko