Re: [PATCH] cpufreq: Remove CPUFREQ_STICKY flag

From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linux OMAP Mailing List <linux-omap@vger.kernel.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Kevin Hilman <khilman@kernel.org>,
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	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Linux PM <linux-pm@vger.kernel.org>,
	Rafael Wysocki <rjw@rjwysocki.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Linux Samsung SoC <linux-samsung-soc@vger.kernel.org>,
	Andy Gross <agross@kernel.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	"moderated list:ARM/Mediatek SoC..."
	<linux-mediatek@lists.infradead.org>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Keguang Zhang <keguang.zhang@gmail.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] cpufreq: Remove CPUFREQ_STICKY flag
Date: Mon, 1 Feb 2021 15:02:06 +0100	[thread overview]
Message-ID: <CAJZ5v0iowSHeie2HLPjHUftBDVBQXi30O1Kfk3Kxchc0K=gYag@mail.gmail.com> (raw)
In-Reply-To: <20210201100502.xluaj5rpqosqsq7b@vireshk-i7>

On Mon, Feb 1, 2021 at 11:06 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 01-02-21, 10:44, Dominik Brodowski wrote:
> > IIRC, it was required on various ARM systems,[*] as CPUs were registered as
> > subsys_initcall(), while cpufreq used to be initialized only later, as an
>
> s/later/earlier ? arch happens before subsys not at least and that is
> the only way we can break cpufreq here, i.e. when the driver comes up
> before the CPUs are registered.
>
> > arch_initcall(). If the ordering is opposite now on all architectures (it
> > wasn't on ARM back then), we should be fine.
> >
> > [*] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/arch/arm/mach-sa1100/cpu-sa1100.c?id=f59d3bbe35f6268d729f51be82af8325d62f20f5
>
> Thanks for your reply, it made me look at that aspect in some more
> detail to confirm I don't end up breaking anything. Unless I am making
> a mistake in reading the code, this is the code flow that we have
> right now:
>
> start_kernel()
> -> kernel_init()
>    -> kernel_init_freeable()
>       -> do_basic_setup()
>          -> driver_init()
>             -> cpu_dev_init()
>                -> subsys_system_register(for-CPUs)
>
>          -> do_initcalls()
>             -> register-cpufreq-driver from any level
>
> And so CPUs should always be there for a cpufreq driver.
>
> Makes sense ?

It does to me, but can you update the changelog, please?

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