linux-kernel - Re: [PATCH -v2] cpufreq: skip loading acpi_cpufreq after intel

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Date:	Fri, 20 Sep 2013 12:51:08 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH -v2] cpufreq: skip loading acpi_cpufreq after intel_pstate

On Fri, Sep 20, 2013 at 10:43 AM, Yinghai Lu <yinghai@...nel.org> wrote:
> If the hw support intel_pstate and acpi_cpufreq, intel_pstate will
> get loaded first.
>
> acpi_cpufreq_init will call acpi_cpufreq_early_init()
> and that will allocate perf data and init those perf data in ACPI core,
> (that will cover all cpus). But later it will free them as
> cpufreq_register_driver(acpi_cpufreq) will fail as init_pstate is
> already registered
>
> Use cpufreq_get_current_driver() to check if we can skip the
> acpi_cpufreq loading.
>
> -v2: update changelog and separate second part to another patch, according
>      to Viresh.
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>
> ---
>  drivers/cpufreq/acpi-cpufreq.c |    4 ++++
>  1 file changed, 4 insertions(+)
>
> Index: linux-2.6/drivers/cpufreq/acpi-cpufreq.c
> ===================================================================
> --- linux-2.6.orig/drivers/cpufreq/acpi-cpufreq.c
> +++ linux-2.6/drivers/cpufreq/acpi-cpufreq.c
> @@ -986,6 +986,10 @@ static int __init acpi_cpufreq_init(void
>  {
>         int ret;
>
> +       /* don't keep reloading if cpufreq_driver exists */
> +       if (cpufreq_get_current_driver())
> +               return 0;
> +
>         if (acpi_disabled)
>                 return 0;
>

only this one is needed, other one

cpufreq: fix racing between acpi_cpufreq_loading

is not needed.

Thanks

Yinghai
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