From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Mike Turquette <mturquette@linaro.org>,
Kevin Hilman <khilman@kernel.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Grant Likely <grant.likely@secretlab.ca>,
Rob Herring <robh+dt@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
ssantosh@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 1/2] ARM: keystone: pm: switch to use generic pm domains
Date: Tue, 25 Nov 2014 14:04:41 +0000 [thread overview]
Message-ID: <20141125140440.GF3836@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <5474846C.2000308@ti.com>
On Tue, Nov 25, 2014 at 03:30:20PM +0200, Grygorii Strashko wrote:
> On 11/25/2014 02:09 PM, Arnd Bergmann wrote:
> > It might be possible to do this implicitly if the driver calls clk_get(),
> > basically doing clk_get() (or another call if necessary) would prevent the
> > simple pmdomain from turning it off during suspend.
>
> Unfortunately, clk_get() will not work, because drivers still need to use it
> to get functional clocks even if they are not going to control them explicitly.
> For example, if it need to know clock's rate.
If you don't want a clock to be turned off, then clk_get() it, then
clk_prepare() it, and finally clk_enable() it.
Even if someone else gets it, the only time that a clock is turned off
is when _all_ users of it mutually agree that it can be turned off - by
every user disabling (and possibly unpreparing) it.
So, if the PM domain code gets a clock, prepares and enables it, then
a driver gets the same clock, prepares and enables it also, it won't
be disabled until _both_ the PM domain code _and_ the driver disable
and unprepare the clock.
--
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2014-11-25 14:04 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-10 14:59 [PATCH v4 0/2] ARM: keystone: pm: switch to use generic pm domains Grygorii Strashko
2014-11-10 14:59 ` [PATCH v4 1/2] " Grygorii Strashko
2014-11-10 15:06 ` Arnd Bergmann
2014-11-10 17:38 ` Grygorii Strashko
2014-11-10 20:36 ` Arnd Bergmann
2014-11-17 19:14 ` Kevin Hilman
[not found] ` <7h389h3aif.fsf-1D3HCaltpLuhEniVeURVKkEOCMrvLtNR@public.gmane.org>
2014-11-17 20:37 ` Arnd Bergmann
2014-11-17 21:50 ` Kevin Hilman
2014-11-18 18:54 ` Grygorii Strashko
2014-11-18 19:32 ` Arnd Bergmann
2014-11-19 11:32 ` Grygorii Strashko
2014-11-19 13:47 ` Arnd Bergmann
2014-11-20 11:34 ` Ulf Hansson
2014-11-20 12:03 ` Grygorii Strashko
2014-11-20 13:12 ` Ulf Hansson
2014-11-20 13:32 ` Geert Uytterhoeven
2014-11-20 15:32 ` Grygorii Strashko
2014-11-20 20:22 ` Kevin Hilman
2014-11-20 20:26 ` Geert Uytterhoeven
2014-11-20 21:48 ` Kevin Hilman
2014-11-20 21:54 ` Geert Uytterhoeven
[not found] ` <CAMuHMdVXGPu7x706NxqO3rn3KuRbPbD_ZQsJtDH4Hf31AaRR+Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-11-21 1:30 ` Kevin Hilman
[not found] ` <7hppchpcfm.fsf-1D3HCaltpLuhEniVeURVKkEOCMrvLtNR@public.gmane.org>
2014-11-21 8:06 ` Geert Uytterhoeven
2014-11-21 18:58 ` Grygorii Strashko
[not found] ` <546F8B39.1080106-l0cyMroinI0@public.gmane.org>
2014-11-21 19:29 ` Kevin Hilman
2014-11-21 20:14 ` Grygorii Strashko
2014-11-24 10:50 ` Arnd Bergmann
2014-11-25 6:44 ` Mike Turquette
2014-11-25 10:33 ` Arnd Bergmann
2014-11-25 11:08 ` Grygorii Strashko
[not found] ` <54746349.3000306-l0cyMroinI0@public.gmane.org>
2014-11-25 12:09 ` Arnd Bergmann
2014-11-25 13:30 ` Grygorii Strashko
2014-11-25 14:04 ` Russell King - ARM Linux [this message]
2014-11-25 14:53 ` Grygorii Strashko
2014-11-25 16:28 ` santosh shilimkar
[not found] ` <CAMuHMdU6G35SP-P7bt6RJQk59CrGcKE2XM4N3o8Dv3qxZU7gxA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-11-21 19:20 ` Kevin Hilman
[not found] ` <546E0970.5090301-l0cyMroinI0@public.gmane.org>
2014-11-21 9:04 ` Geert Uytterhoeven
2014-11-18 2:18 ` santosh.shilimkar
2014-11-10 14:59 ` [PATCH v4 2/2] ARM: dts: keystone: add generic pm controller node Grygorii Strashko
2014-11-10 15:13 ` [PATCH v4 0/2] ARM: keystone: pm: switch to use generic pm domains Grygorii Strashko
[not found] ` <5460D601.70504-l0cyMroinI0@public.gmane.org>
2014-11-10 18:51 ` santosh.shilimkar-QHcLZuEGTsvQT0dZR+AlfA
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