linux-kernel - Re: [PATCH 3/4] PM / devfreq: Kconfig: add DEVFREQ_DELAYED

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Message-ID: <4b1b94e9-890a-cce1-c33d-33864c7ed230@samsung.com>
Date:   Tue, 10 Dec 2019 10:54:38 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Kamil Konieczny <k.konieczny@...sung.com>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Subject: Re: [PATCH 3/4] PM / devfreq: Kconfig: add DEVFREQ_DELAYED_TIMER
 option

On 12/9/19 11:44 PM, Kamil Konieczny wrote:
> Add Kconfig option DEVFREQ_DELAYED_TIMER. If set, devfreq workqueue
> will use delayed timer from its start.
> 
> Signed-off-by: Kamil Konieczny <k.konieczny@...sung.com>
> ---
>  drivers/devfreq/Kconfig | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> index 38a94df749a2..c799917c34c9 100644
> --- a/drivers/devfreq/Kconfig
> +++ b/drivers/devfreq/Kconfig
> @@ -74,6 +74,18 @@ config DEVFREQ_GOV_PASSIVE
>  	  through sysfs entries. The passive governor recommends that
>  	  devfreq device uses the OPP table to get the frequency/voltage.
>  
> +comment "DEVFREQ Options"
> +
> +config DEVFREQ_DELAYED_TIMER
> +	bool "Use delayed timer in Simple Ondemand Governor"
> +	default false
> +	help
> +	  Simple Ondemand Governor uses polling for reading buses counters.
> +	  A default timer used is deferred, which saves power, but can
> +	  miss increased demand for higher bus frequency if timer was
> +	  assigned to idle cpu. If you want to change this to delayed
> +	  timer at the cost of more power used, say Yes here.
> +
>  comment "DEVFREQ Drivers"

I don't think that we cannot choice the all options in Kconfig
at the build time. If we add something like this patch,

we can choice the any options in Kconfig as following:
- polling time (millisecond)
- up threshold
- down threshold
- type of workqueue
- etc ...

Also, there are too much optional value and selectable value 
in the linux kernel. 

As I said, If you suggest the reasonable data with test result,
I will add the new flag to 'struct devfreq_dev_profile'.

>  
>  config ARM_EXYNOS_BUS_DEVFREQ
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics