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Date: Wed, 12 Aug 2015 10:02:53 -0500
From: Felipe Balbi <balbi@ti.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
CC: Grygorii Strashko <grygorii.strashko@ti.com>,
        Michael Turquette
	<mturquette@baylibre.com>,
        Nishanth Menon <nm@ti.com>, Thomas Gleixner
	<tglx@linutronix.de>,
        <linux-rt-users@vger.kernel.org>, Felipe Balbi
	<balbi@ti.com>,
        Sekhar Nori <nsekhar@ti.com>, <linux-clk@vger.kernel.org>
Subject: Re: Common clock framework API vs RT patchset
Message-ID: <20150812150253.GE13884@saruman.tx.rr.com>
Reply-To: <balbi@ti.com>
References: <55C0A96F.80307@ti.com>
 <alpine.DEB.2.11.1508041405290.3983@nanos>
 <55C0D8F3.3030105@ti.com>
 <20150804153641.GR7557@n2100.arm.linux.org.uk>
 <55CA4BC2.4020505@ti.com>
 <20150811192514.GB7557@n2100.arm.linux.org.uk>
 <20150811220609.31346.15943@quantum>
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 <20150812101151.GK7557@n2100.arm.linux.org.uk>
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On Wed, Aug 12, 2015 at 11:11:51AM +0100, Russell King - ARM Linux wrote:
> On Wed, Aug 12, 2015 at 01:05:58PM +0300, Grygorii Strashko wrote:
> > On 08/12/2015 01:06 AM, Michael Turquette wrote:
> > > Quoting Russell King - ARM Linux (2015-08-11 12:25:15)
> > >>
> > >> clk_enable/clk_disable _should_ be usable from atomic contexts.
> >=20
> > Thanks Russell - above is not true on -RT.
>=20
> What I'm saying is that it _should_ be true.  You _should_ be able to
> call clk_enable()/clk_disable() from atomic contexts.  It's been
> documented since forever:
>=20
> /**
>  * clk_enable - inform the system when the clock source should be running.
>  * @clk: clock source
>  *
>  * If the clock can not be enabled/disabled, this should return success.
>  *
>  * May be called from atomic contexts.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>=20
> /**
>  * clk_disable - inform the system when the clock source is no longer req=
uired.
>  * @clk: clock source
>  *
>  * Inform the system that a clock source is no longer required by
>  * a driver and may be shut down.
>  *
>  * May be called from atomic contexts.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>=20
> If that's not true with CCF, that's a CCF bug, not a usage bug.

in that case, CCF's clock need to be converted to raw_spin_locks, that's
the only way to prevent its locks from being reimplemented as rt
mutexes.

--=20
balbi

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