From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1947202AbcHRLB1 (ORCPT ); Thu, 18 Aug 2016 07:01:27 -0400 Received: from cloudserver094114.home.net.pl ([79.96.170.134]:51517 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1945959AbcHRLBX (ORCPT ); Thu, 18 Aug 2016 07:01:23 -0400 From: "Rafael J. Wysocki" To: Sudeep Holla Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Gross , Lorenzo Pieralisi Subject: Re: [PATCH] PM / sleep: enable suspend-to-idle even without registered suspend_ops Date: Thu, 18 Aug 2016 13:06:49 +0200 Message-ID: <1549989.BLB0oyvVbJ@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.8.0-rc1+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1471511964-6341-1-git-send-email-sudeep.holla@arm.com> References: <1471511964-6341-1-git-send-email-sudeep.holla@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, August 18, 2016 10:19:24 AM Sudeep Holla wrote: > Suspend-to-idle (aka the "freeze" sleep state) is a system sleep state > in which all of the processors enter deepest possible idle state and > wait for interrupts right after suspending all the devices. > > There is no hard requirement for a platform to support and register > platform specific suspend_ops to enter suspend-to-idle/freeze state. > Only deeper system sleep states like PM_SUSPEND_STANDBY and > PM_SUSPEND_MEM rely on such low level support/implementation. > > suspend-to-idle can be entered as along as all the devices can be > suspended. This patch enables the support for suspend-to-idle even on > systems that don't have any low level support for deeper system sleep > states and/or don't register any platform specific suspend_ops. > > Cc: "Rafael J. Wysocki" > Signed-off-by: Sudeep Holla > --- > kernel/power/main.c | 5 +++++ > kernel/power/suspend.c | 8 +++++--- > 2 files changed, 10 insertions(+), 3 deletions(-) > > Hi Rafael, > > I am not sure if you like this approach. I found this to be the simplest > but I may have missed to consider all possible corner cases especially > for x86 and other platforms. I don't see any such issues/cases with ARM > systems. > > diff --git a/kernel/power/main.c b/kernel/power/main.c > index 5ea50b1b7595..0f0fd9184f39 100644 > --- a/kernel/power/main.c > +++ b/kernel/power/main.c > @@ -651,6 +651,11 @@ static int __init pm_init(void) > if (error) > return error; > pm_print_times_init(); > + /* > + * freeze state should be supported even without any suspend_ops, > + * calling suspend_set_ops without any ops will setup freeze state > + */ > + suspend_set_ops(NULL); Well, this is a core initcall, so suspend_set_ops() invocations from platforms really should happen after that, so something like this should be sufficient here: pm_state[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? PM_SUSPEND_MEM : PM_SUSPEND_FREEZE]; if I'm not mistaken. > return pm_autosleep_init(); > } > diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c > index 0acab9d7f96f..37d64f811ecd 100644 > --- a/kernel/power/suspend.c > +++ b/kernel/power/suspend.c > @@ -138,7 +138,9 @@ void suspend_set_ops(const struct platform_suspend_ops *ops) > > lock_system_sleep(); > > - suspend_ops = ops; > + WARN_ONCE(ops && suspend_ops, "overriding suspend_ops"); > + if (ops) > + suspend_ops = ops; And this should not be necessary then. > for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--) > if (valid_state(i)) { > pm_states[i] = pm_labels[j++]; > @@ -211,7 +213,7 @@ static int platform_suspend_begin(suspend_state_t state) > { > if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->begin) > return freeze_ops->begin(); > - else if (suspend_ops->begin) > + else if (suspend_ops && suspend_ops->begin) > return suspend_ops->begin(state); > else > return 0; > @@ -221,7 +223,7 @@ static void platform_resume_end(suspend_state_t state) > { > if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->end) > freeze_ops->end(); > - else if (suspend_ops->end) > + else if (suspend_ops && suspend_ops->end) > suspend_ops->end(); > } And this is still needed, of course. Thanks, Rafael