Re: [net-next, v5, 02/11] ptp: support ptp physical/virtual clocks conversion

From: Richard Cochran <richardcochran@gmail.com>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Vinicius Costa Gomes <vinicius.gomes@intel.com>,
	Yangbo Lu <yangbo.lu@nxp.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org, mptcp@lists.linux.dev,
	"David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Mat Martineau <mathew.j.martineau@linux.intel.com>,
	Matthieu Baerts <matthieu.baerts@tessares.net>,
	Shuah Khan <shuah@kernel.org>, Michal Kubecek <mkubecek@suse.cz>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>, Rui Sousa <rui.sousa@nxp.com>,
	Sebastien Laveze <sebastien.laveze@nxp.com>
Subject: Re: [net-next, v5, 02/11] ptp: support ptp physical/virtual clocks conversion
Date: Sat, 7 Aug 2021 13:56:44 -0700	[thread overview]
Message-ID: <20210807205644.GD22362@hoboy.vegasvil.org> (raw)
In-Reply-To: <20210807144332.szyazdfl42abwzmd@skbuf>

On Sat, Aug 07, 2021 at 05:43:32PM +0300, Vladimir Oltean wrote:
> >  3. Let the vclocks hold a reference to the underlying posix dynamic clock.
> 
> So even if the vclock holds a reference to the underlying POSIX clock,
> that won't prevent the hardware driver from unbinding, and further
> gettime() calls on the vclock from faulting, will it?

Oh, your are right.  The vclocks call the real PHC clock's methods
directly, not through the posix dynamic clock layer.

> What about:
> 
> 4. Create a device link with the vclock being a consumer and the parent
>    clock being a supplier? This way, ptp_vclock_unregister() is
>    automatically called whenever (and before) ptp_clock_unregister() is.
> 
> https://www.kernel.org/doc/html/latest/driver-api/device_link.html

Sounds promising.

Thanks,
Richard