linux-kernel - Re: [PATCH v3 2/2] cpufreq: CPPC: Change FIE default

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Date:   Wed, 24 Aug 2022 11:44:30 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Jeremy Linton <jeremy.linton@....com>
Cc:     linux-acpi@...r.kernel.org, rafael@...nel.or, lenb@...nel.org,
        robert.moore@...el.com, punit.agrawal@...edance.com,
        lukasz.luba@....com, ionela.voinescu@....com,
        pierre.gondois@....com, linux-kernel@...r.kernel.org,
        devel@...ica.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 2/2] cpufreq: CPPC: Change FIE default

On 18-08-22, 16:16, Jeremy Linton wrote:
> FIE is mostly implemented as PCC mailboxes on arm machines.  This was
> enabled by default without any data suggesting that it does anything
> but hurt system performance. Lets change the default to 'n' until
> hardware appears which clearly benefits.
> 
> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
> ---
>  drivers/cpufreq/Kconfig.arm | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 954749afb5fe..ad66d8f15db0 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -22,7 +22,7 @@ config ACPI_CPPC_CPUFREQ
>  config ACPI_CPPC_CPUFREQ_FIE
>  	bool "Frequency Invariance support for CPPC cpufreq driver"
>  	depends on ACPI_CPPC_CPUFREQ && GENERIC_ARCH_TOPOLOGY
> -	default y
> +	default n
>  	help
>  	  This extends frequency invariance support in the CPPC cpufreq driver,
>  	  by using CPPC delivered and reference performance counters.

Why is this required after we have the first patch in ?

-- 
viresh