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From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>,
	Romain Izard <romain.izard.pro@gmail.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Alexandre Belloni <alexandre.belloni@free-electrons.com>
Subject: Re: [PATCH v1] clocksource: atmel-pit: register as a sched_clock
Date: Mon, 8 Feb 2016 15:06:14 +0100	[thread overview]
Message-ID: <20160208150614.5e87133e@bbrezillon> (raw)
In-Reply-To: <56B89910.3060305@linaro.org>

+ Alexandre

Hi Daniel,

On Mon, 8 Feb 2016 14:33:04 +0100
Daniel Lezcano <daniel.lezcano@linaro.org> wrote:

> On 02/04/2016 06:21 PM, Romain Izard wrote:
> > Register the counter of the Periodic Interval Timer as a possible source
> > for sched_clock. This provides a better precision than the jiffies-based
> > default.
> >
> > Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
> 
> Nicolas, Boris,
> 
> Are you ok with this patch ?

Not sure yet :). On most platforms we are also declaring a clocksource
based on the TCB IP, and this one provides a better precision than the
PIT clocksource.
What happens if the PIT is de-activated while it's still supposed to
provide the sched_clock(). Is there a way to flag the clocksource as
still needed so that the core does not shut it down by when the TCB
clocksource comes in.

Best Regards,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

WARNING: multiple messages have this Message-ID (diff)
From: boris.brezillon@free-electrons.com (Boris Brezillon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v1] clocksource: atmel-pit: register as a sched_clock
Date: Mon, 8 Feb 2016 15:06:14 +0100	[thread overview]
Message-ID: <20160208150614.5e87133e@bbrezillon> (raw)
In-Reply-To: <56B89910.3060305@linaro.org>

+ Alexandre

Hi Daniel,

On Mon, 8 Feb 2016 14:33:04 +0100
Daniel Lezcano <daniel.lezcano@linaro.org> wrote:

> On 02/04/2016 06:21 PM, Romain Izard wrote:
> > Register the counter of the Periodic Interval Timer as a possible source
> > for sched_clock. This provides a better precision than the jiffies-based
> > default.
> >
> > Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
> 
> Nicolas, Boris,
> 
> Are you ok with this patch ?

Not sure yet :). On most platforms we are also declaring a clocksource
based on the TCB IP, and this one provides a better precision than the
PIT clocksource.
What happens if the PIT is de-activated while it's still supposed to
provide the sched_clock(). Is there a way to flag the clocksource as
still needed so that the core does not shut it down by when the TCB
clocksource comes in.

Best Regards,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

  reply	other threads:[~2016-02-08 14:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-04 17:21 [PATCH v1] clocksource: atmel-pit: register as a sched_clock Romain Izard
2016-02-04 17:21 ` Romain Izard
2016-02-08 13:33 ` Daniel Lezcano
2016-02-08 13:33   ` Daniel Lezcano
2016-02-08 14:06   ` Boris Brezillon [this message]
2016-02-08 14:06     ` Boris Brezillon

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