From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754731AbbATLNz (ORCPT ); Tue, 20 Jan 2015 06:13:55 -0500 Received: from www.linutronix.de ([62.245.132.108]:47963 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753492AbbATLNw (ORCPT ); Tue, 20 Jan 2015 06:13:52 -0500 Date: Tue, 20 Jan 2015 12:13:08 +0100 (CET) From: Thomas Gleixner To: Alexandre Belloni cc: John Stultz , Daniel Lezcano , Nicolas Ferre , Boris Brezillon , Russell King - ARM Linux , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [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> Message-ID: References: <1421427439-11699-1-git-send-email-alexandre.belloni@free-electrons.com> <1421427439-11699-3-git-send-email-alexandre.belloni@free-electrons.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.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