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From: Dmitry Osipenko <digetx@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>,
	Peter De Schrijver <pdeschrijver@nvidia.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 08/14] ARM: tegra: Make outer_disable() open-coded
Date: Mon, 30 Sep 2019 17:29:13 +0300	[thread overview]
Message-ID: <a23edc5b-97c6-9dae-589e-b71d07069b0c@gmail.com> (raw)
In-Reply-To: <20190930080511.GE1518582@ulmo>

30.09.2019 11:05, Thierry Reding пишет:
> On Sun, Sep 29, 2019 at 08:59:46PM +0300, Dmitry Osipenko wrote:
>> The outer_disable() of Tegra's suspend code is open-coded now since
>> that helper produces spurious warning message about secondary CPUs being
>> online. The secondaries are actually halted by the cpuidle driver on
>> entering into LP2 idle-state. This fixes a storm of warnings once LP2
>> idling state is enabled on Tegra30.
> 
> If the cpuidle driver halts the secondaries, shouldn't it set it offline
> then so that outer_disable() can still work correctly?

No.. how would you know what CPU's should be resumed?

AFAIK, the online status should be only changed by the hotplug code and
nothing else. I don't think that it's a good idea to manually touch the
online mask.

It looks to me that the only purpose of outer_disable() checking for the
num_online_cpus is to prevent people from doing wrong things by
disabling L2 in a random places in their code. Hence it should be
absolutely fine to open code when you know what you're doing, which is
the case here.

We can check the rail status in tegra_sleep_cpu():

if (trusted_foundations_registered() && outer_cache.disable) {
	if (WARN_ON(!tegra_cpu_rail_off_ready()))
		return -EBUSY;

	outer_cache.disable();
}

Which is equal to the check for num_online_cpus. Does it sound good?

  reply	other threads:[~2019-09-30 14:29 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-29 17:59 [PATCH v5 00/14] Consolidate and improve NVIDIA Tegra CPUIDLE driver(s) Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 01/14] ARM: tegra: Remove cpuidle drivers to replace them with a new driver Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 02/14] ARM: tegra: Change tegra_set_cpu_in_lp2() type to void Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 03/14] ARM: tegra: Propagate error from tegra_idle_lp2_last() Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 04/14] ARM: tegra: Compile sleep-tegra20/30.S unconditionally Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 05/14] ARM: tegra: Expose PM functions required for new cpuidle driver Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 06/14] ARM: tegra: Rename some of the newly exposed PM functions Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 07/14] ARM: tegra: Add tegra_pm_park_secondary_cpu() Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 08/14] ARM: tegra: Make outer_disable() open-coded Dmitry Osipenko
2019-09-30  8:05   ` Thierry Reding
2019-09-30 14:29     ` Dmitry Osipenko [this message]
2019-09-29 17:59 ` [PATCH v5 09/14] clk: tegra: Add missing stubs for the case of !CONFIG_PM_SLEEP Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 10/14] cpuidle: Introduce unified driver for NVIDIA Tegra SoCs Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 11/14] cpuidle: tegra: Support CPU cluster power-down state on Tegra30 Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 12/14] ARM: tegra: Create simple platform device for cpuidle driver Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 13/14] ARM: multi_v7_defconfig: Enable Tegra " Dmitry Osipenko
2019-09-29 17:59 ` [PATCH v5 14/14] ARM: tegra: Enable Tegra cpuidle driver in tegra_defconfig Dmitry Osipenko
2019-09-30  8:26 ` [PATCH v5 00/14] Consolidate and improve NVIDIA Tegra CPUIDLE driver(s) Thierry Reding
2019-09-30 18:32   ` Dmitry Osipenko

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