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Date:   Tue, 3 Mar 2020 07:23:17 -0800
From:   Richard Cochran <richardcochran@gmail.com>
To:     Linus Walleij <linus.walleij@linaro.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Jonathan Cameron <jic23@kernel.org>,
        "Christopher S. Hall" <christopher.s.hall@intel.com>,
        netdev <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        jacob.e.keller@intel.com, "David S. Miller" <davem@davemloft.net>,
        Sean V Kelley <sean.v.kelley@intel.com>
Subject: Re: [Intel PMC TGPIO Driver 0/5] Add support for Intel PMC Time GPIO
 Driver with PHC interface changes to support additional H/W Features
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On Tue, Mar 03, 2020 at 02:00:48PM +0100, Linus Walleij wrote:
> 
> That looks like something I/we would want to support all the way
> to userspace so people can do their funny industrial stuff in some
> standard manner.

...

> HW timestamps would be something more elaborate and
> nice CLOCK_HW_SPECIFIC or so. Some of the IIO sensors also
> have that, we just don't expose it as of now.

It is worth considering whether it makes sense to somehow unify gpio,
iio, and the phc pin subsystems.  In my view, a big chunk of work
would be to have something like the "clock tree" for gpios and clock
lines.  This tree would describe the HW connectivity between (at
least) MAC/PHY clocks and IOs, gpio controllers, audio/video codecs,
and so on.

Also, there is that comedi thing in staging.  If it has a chance ever
to leave staging, then I think it would also benefit from integration
into gpio/iio world.

Thanks,
Richard