Re: [RFC] Periodic Output, Timestamped Input

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Tue, Dec 5, 2017 at 10:20 AM, Felipe Balbi
<felipe.balbi@xxxxxxxxxxxxxxx> wrote:
> [Me]:

>> I was thinking about it already when implementing it but it fell
>> out of my mind. I'm putting in on my TODO. (CC to bartosz
>> who might be interested, he's using these ABIs quite a bit.)
>
> fair enough. In that case, it'll probably be easier to implement
> HW-based timestamping with something like below:

Indeed.

IIO has a per-device sysfs file for setting up
the POSIX timestamping named current_timestamp_clock.
This was added by Gregor Boire in commit
bc2b7dab629a

The supported timestamps are:
realtime
monotonic
monotonic_raw
realtime_coarse
monotonic_coarse
boottime
tai

I could really need some help here... :/

It feels like "monotonic" could very well be what you're
looking for but I don't know the POSIX definition of these.
Maybe we need to add one more for "device specific"?

What I want to do is factor most of that commit out into
lib/ and reuse for timestamping in GPIO so we can
have coherent timestamps across GPIO and IIO.

OK OK O need to get to it and stop talking...

I guess it should be set per-gpiochip rather than
per-gpio-desc though, but that makes most sense anyways.

Yours,
Linus Walleij
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