From mboxrd@z Thu Jan 1 00:00:00 1970 From: tglx@linutronix.de (Thomas Gleixner) Date: Tue, 20 Jan 2015 12:13:08 +0100 (CET) Subject: [PATCH v2 2/2] clocksource: don't suspend/resume when unused In-Reply-To: <1421427439-11699-3-git-send-email-alexandre.belloni@free-electrons.com> References: <1421427439-11699-1-git-send-email-alexandre.belloni@free-electrons.com> <1421427439-11699-3-git-send-email-alexandre.belloni@free-electrons.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, 16 Jan 2015, Alexandre Belloni wrote: > There is no point in calling suspend/resume for unused > clocksources. That's true, but .... > Signed-off-by: Alexandre Belloni > --- > kernel/time/clocksource.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c > index 03cfc5a08e3b..da65b3b73a86 100644 > --- a/kernel/time/clocksource.c > +++ b/kernel/time/clocksource.c > @@ -493,7 +493,7 @@ void clocksource_suspend(void) > struct clocksource *cs; > > list_for_each_entry_reverse(cs, &clocksource_list, list) > - if (cs->suspend) > + if (cs->suspend && (cs->flags & CLOCK_SOURCE_USED)) > cs->suspend(cs); > } > > @@ -505,7 +505,7 @@ void clocksource_resume(void) > struct clocksource *cs; > > list_for_each_entry(cs, &clocksource_list, list) > - if (cs->resume) > + if (cs->resume && (cs->flags & CLOCK_SOURCE_USED)) > cs->resume(cs); I had a deeper look at the clocksources which have a resume callback. We have implementations, which rely on the resume callback being called unconditionally. e.g.: arch/x86/kernel/hpet.c. And there are a few others which have extra PM code in the suspend/resume path independent of the fact whether the clocksource is enabled or not. So we really need to make this opt-in with a per clocksource flag. Thanks, tglx