linux-kernel - Re: [PATCH] clockevents: don't suspend/resume if unused

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Message-ID: <20150116111706.GE12302@n2100.arm.linux.org.uk>
Date:	Fri, 16 Jan 2015 11:17:06 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Sylvain Rochet <sylvain.rochet@...secur.com>
Cc:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] clockevents: don't suspend/resume if unused

On Fri, Jan 16, 2015 at 10:20:14AM +0100, Sylvain Rochet wrote:
> Hello Alexandre,
> 
> 
> On Fri, Jan 16, 2015 at 10:05:51AM +0100, Alexandre Belloni wrote:
> > There is no point in calling suspend/resume for unused
> > clockevents as they are already stopped and disabled.
> > 
> > Furthermore, it can take some time to wait for some IPs to stop counting.
> > 
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> > Reported-by: Sylvain Rochet <sylvain.rochet@...secur.com>
> 
> Indeed, this is way better from what I did.
> 
> 
> > +		if (dev->suspend && dev->mode != CLOCK_EVT_MODE_UNUSED)
> 
> I wonder if we should use > CLOCK_EVT_MODE_SHUTDOWN
> (or CLOCK_EVT_MODE_UNUSED || CLOCK_EVT_MODE_SHUTDOWN) instead of 
> !CLOCK_EVT_MODE_UNUSED.

Definitely - consider the effect of the original patch set on a clock
source which is being used, has PM support, but does not have an
->enable callback.

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