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From: Lars-Peter Clausen <lars@metafoo.de>
To: Gregor Boirie <gregor.boirie@parrot.com>, linux-iio@vger.kernel.org
Subject: Re: using monotonic clok for timstamping
Date: Wed, 3 Feb 2016 12:22:00 +0100	[thread overview]
Message-ID: <56B1E2D8.90308@metafoo.de> (raw)
In-Reply-To: <56B1DCA4.9050903@parrot.com>

On 02/03/2016 11:55 AM, Gregor Boirie wrote:
> Dear  all,
> 
> Our application relies on precise and monotonic timestamping of IMU samples
> (and other sensors).
> I am wondering what reasons / use cases led to the choice of realtime clock
> to implement
> iio_get_time_ns (not to mention time gaps that may be seen after wake up
> from sleep states).

It's more of an oversight than a deliberate design decision. I noticed this
problem as well a while ago and wanted to re-write things to use the
monotonic clock, but then realized that this would be a ABI change so
dropped it and forgot about it again.

> 
> As a dirty hack, I simply rewrote iio_get_time_ns on our platform. But I
> suspect it would be usefull as
> a long term solution, to give userland the ability to choose a particular
> posix clock (realtime, monotonic,
> etc...) on a per device and / or driver basis through a sysfs attribute for
> example.

This is probably the only viable solution while keeping the ABI backwards
compatible.

- Lars


  reply	other threads:[~2016-02-03 11:22 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-03 10:55 Gregor Boirie
2016-02-03 11:22 ` Lars-Peter Clausen [this message]
2016-02-06 18:33   ` Jonathan Cameron
2016-02-08  9:55     ` Lars-Peter Clausen
2016-02-08 17:15       ` Jonathan Cameron
2016-02-09 11:06         ` Gregor Boirie
2016-02-09 14:19           ` Gregor Boirie
2016-02-09 20:49             ` Jonathan Cameron
2016-02-09 20:52           ` Lars-Peter Clausen
2016-02-09 21:02             ` Jonathan Cameron
2016-02-10  9:46             ` Gregor Boirie

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