linux-kernel - Re: [PATCH 5/5] cpufreq: qcom-hw: Move driver initialisation earlier

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Message-ID: <20190917093412.GA24757@bogus>
Date:   Tue, 17 Sep 2019 10:34:12 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Amit Kucheria <amit.kucheria@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        bjorn.andersson@...aro.org, edubezval@...il.com, agross@...nel.org,
        tdas@...eaurora.org, swboyd@...omium.org, ilina@...eaurora.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Sudeep Holla <sudeep.holla@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Zhang Rui <rui.zhang@...el.com>, linux-pm@...r.kernel.org
Subject: Re: [PATCH 5/5] cpufreq: qcom-hw: Move driver initialisation earlier

On Thu, Sep 12, 2019 at 04:02:34AM +0530, Amit Kucheria wrote:
> Allow qcom-hw driver to initialise right after the cpufreq and thermal
> subsystems are initialised in core_initcall so we get earlier access to
> thermal mitigation.
>
> Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> ---
>  drivers/cpufreq/qcom-cpufreq-hw.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index 4b0b50403901..04676cc82ba6 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -327,7 +327,7 @@ static int __init qcom_cpufreq_hw_init(void)
>  {
>  	return platform_driver_register(&qcom_cpufreq_hw_driver);
>  }
> -device_initcall(qcom_cpufreq_hw_init);
> +postcore_initcall(qcom_cpufreq_hw_init);

I am fine with core framework initcall pushed to earlier initcall levels
if required, but for individual/platform specific drivers I am not so
happy to see that.

This goes against the grand plan of single common kernel strategy by
Android moving all drivers as modules. We might decide to make this
a module. Also there are few cpufreq drivers that are modules. Will
they have issues ? If not, why do we need this change at all. Needing
thermal mitigation during boot this earlier is still too much of
expectation, I would rather boot slowly than relying on this feature.

--
Regards,
Sudeep