From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Kent Gibson <warthog618@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Linus Walleij <linus.walleij@linaro.org>,
Jack Winch <sunt.un.morcov@gmail.com>
Subject: Re: [PATCH v2 1/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME
Date: Fri, 16 Oct 2020 17:13:22 +0300 [thread overview]
Message-ID: <CAHp75VcAf8i=jEdDFntpDfLBDMWoJh+ykHBTBRX53B9L+yFNUA@mail.gmail.com> (raw)
In-Reply-To: <20201014231158.34117-2-warthog618@gmail.com>
On Thu, Oct 15, 2020 at 6:53 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Using CLOCK_REALTIME as the source for event timestamps is crucial for
> some specific applications, particularly those requiring timetamps
> relative to a PTP clock, so provide an option to switch the event
> timestamp source from the default CLOCK_MONOTONIC to CLOCK_REALTIME.
>
> Note that CLOCK_REALTIME was the default source clock for GPIO until
> Linux 5.7 when it was changed to CLOCK_MONOTONIC due to issues with the
> shifting of the realtime clock.
> Providing this option maintains the CLOCK_MONOTONIC as the default,
> while also providing a path forward for those dependent on the pre-5.7
> behaviour.
...
> GPIO_V2_LINE_DIRECTION_FLAGS | \
> GPIO_V2_LINE_DRIVE_FLAGS | \
> GPIO_V2_LINE_EDGE_FLAGS | \
> + GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME | \
Wondering if we would have something like
GPIO_V2_LINE_CLOCK_FLAGS | \
here for the sake of consistency.
> GPIO_V2_LINE_BIAS_FLAGS)
...
> +static u64 line_event_timestamp(struct line *line)
> +{
> + if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &line->desc->flags))
I dunno if we can actually drop the word EVENT from these definitions.
I don't think we would have in the near future something similar for
the non-event data.
> + return ktime_get_real_ns();
> +
> + return ktime_get_ns();
> +}
In general it looks good, thanks!
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-10-16 14:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 23:11 [PATCH v2 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Kent Gibson
2020-10-14 23:11 ` [PATCH v2 1/3] " Kent Gibson
2020-10-16 14:13 ` Andy Shevchenko [this message]
2020-10-16 23:27 ` Kent Gibson
2020-10-14 23:11 ` [PATCH v2 2/3] tools: gpio: add support for reporting realtime event clock to lsgpio Kent Gibson
2020-10-14 23:11 ` [PATCH v2 3/3] tools: gpio: add option to report wall-clock time to gpio-event-mon Kent Gibson
2020-10-28 16:01 ` [PATCH v2 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Linus Walleij
2020-10-28 23:22 ` Kent Gibson
2020-10-30 14:49 ` Bartosz Golaszewski
2020-10-30 14:52 ` Bartosz Golaszewski
2020-10-31 0:01 ` Kent Gibson
2020-11-02 8:56 ` Bartosz Golaszewski
2020-11-06 13:49 ` Linus Walleij
2020-12-01 18:20 ` Bartosz Golaszewski
2020-12-05 22:23 ` Linus Walleij
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