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From: Stephen Boyd <swboyd@chromium.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>,
	Claude Yen <claude.yen@mediatek.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Douglas Anderson <dianders@chromium.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Rafael J. Wysocki <rjw@rjwysocki.net>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: wsd_upstream@mediatek.com, linux-pm@vger.kernel.org,
	"claude.yen" <claude.yen@mediatek.com>,
	linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] PM: s2idle: Introduce syscore callbacks in s2idle flow
Date: Tue, 01 Sep 2020 00:40:23 -0700	[thread overview]
Message-ID: <159894602346.334488.4470501636825871587@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <1598943859-21857-2-git-send-email-claude.yen@mediatek.com>

Quoting Claude Yen (2020-09-01 00:04:19)
> From: "claude.yen" <claude.yen@mediatek.com>
> 
> Adding syscore callbacks to s2idle makes the behavior of s2idle become
> more similar to Suspend-to-Ram (S2R) and reduces potential porting
> effort.
> 
> tick_freeze() in s2idle flow calls sched_clock_suspend() and
> timekeeping_suspend(), which both functions are also registered as
> syscore callback. sched_clock_suspend() introduced in
> commit 3f2552f7e9c5 ("timers/sched_clock: Prevent generic sched_clock
> wrap caused by tick_freeze()") is added due to clock wrap issue.
> By adding syscore callbacks in s2idle, if there is any syscore callbacks
> also required in s2idle, additional porting effort could be saved.
> 
> Besides, in both S2R and s2idle, before the system entering low power
> state, there is a state when only one cpu alive with interrupt-disabled,
> which is syscore callback designed for. Adding syscore callbacks in
> s2idle is feasible option.
> 
> Scenarios to call syscore callback:
> S2R: one cpu alive when nonboot cpus are hotplug-ed off
> s2idle: one cpu alive when other cpus have enter idle state
> 

Do you have syscore ops that can't be converted to something else like
CPU_PM notifier? At this point most syscore code that is important has
been converted so I don't see much benefit for this patch. If anything,
it will prevent conversions to code that works for both cases.

> 
> Signed-off-by: claude.yen <claude.yen@mediatek.com>

_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

WARNING: multiple messages have this Message-ID (diff)
From: Stephen Boyd <swboyd@chromium.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>,
	Claude Yen <claude.yen@mediatek.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Douglas Anderson <dianders@chromium.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Rafael J. Wysocki <rjw@rjwysocki.net>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: wsd_upstream@mediatek.com, linux-pm@vger.kernel.org,
	"claude.yen" <claude.yen@mediatek.com>,
	linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] PM: s2idle: Introduce syscore callbacks in s2idle flow
Date: Tue, 01 Sep 2020 00:40:23 -0700	[thread overview]
Message-ID: <159894602346.334488.4470501636825871587@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <1598943859-21857-2-git-send-email-claude.yen@mediatek.com>

Quoting Claude Yen (2020-09-01 00:04:19)
> From: "claude.yen" <claude.yen@mediatek.com>
> 
> Adding syscore callbacks to s2idle makes the behavior of s2idle become
> more similar to Suspend-to-Ram (S2R) and reduces potential porting
> effort.
> 
> tick_freeze() in s2idle flow calls sched_clock_suspend() and
> timekeeping_suspend(), which both functions are also registered as
> syscore callback. sched_clock_suspend() introduced in
> commit 3f2552f7e9c5 ("timers/sched_clock: Prevent generic sched_clock
> wrap caused by tick_freeze()") is added due to clock wrap issue.
> By adding syscore callbacks in s2idle, if there is any syscore callbacks
> also required in s2idle, additional porting effort could be saved.
> 
> Besides, in both S2R and s2idle, before the system entering low power
> state, there is a state when only one cpu alive with interrupt-disabled,
> which is syscore callback designed for. Adding syscore callbacks in
> s2idle is feasible option.
> 
> Scenarios to call syscore callback:
> S2R: one cpu alive when nonboot cpus are hotplug-ed off
> s2idle: one cpu alive when other cpus have enter idle state
> 

Do you have syscore ops that can't be converted to something else like
CPU_PM notifier? At this point most syscore code that is important has
been converted so I don't see much benefit for this patch. If anything,
it will prevent conversions to code that works for both cases.

> 
> Signed-off-by: claude.yen <claude.yen@mediatek.com>

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2020-09-01  7:40 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-01  7:04 [PATCH] PM: s2idle: Introduce syscore callbacks in s2idle flow Claude Yen
2020-09-01  7:04 ` Claude Yen
2020-09-01  7:04 ` Claude Yen
2020-09-01  7:04 ` [PATCH 1/1] " Claude Yen
2020-09-01  7:04   ` Claude Yen
2020-09-01  7:40   ` Stephen Boyd [this message]
2020-09-01  7:40     ` Stephen Boyd
2020-09-03  3:43     ` Claude.Yen
2020-09-03  3:43       ` Claude.Yen
2020-09-01 11:57 ` [PATCH] " Rafael J. Wysocki
2020-09-01 11:57   ` Rafael J. Wysocki
2020-09-01 11:57   ` Rafael J. Wysocki
2020-09-03  2:14   ` Claude.Yen
2020-09-03  2:14     ` Claude.Yen
2020-09-10 12:55     ` Rafael J. Wysocki
2020-09-10 12:55       ` Rafael J. Wysocki
2020-09-10 12:55       ` Rafael J. Wysocki

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