linux-kernel - Re: [PATCH v8 05/13] cpufreq: amd-pstate: optimize driver working mode selection in amd_pstate

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Date:   Fri, 23 Dec 2022 12:23:48 +0800
From:   Huang Rui <ray.huang@....com>
To:     "Yuan, Perry" <Perry.Yuan@....com>
Cc:     "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        "Limonciello, Mario" <Mario.Limonciello@....com>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
        "Sharma, Deepak" <Deepak.Sharma@....com>,
        "Fontenot, Nathan" <Nathan.Fontenot@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Huang, Shimmer" <Shimmer.Huang@....com>,
        "Du, Xiaojian" <Xiaojian.Du@....com>,
        "Meng, Li (Jassmine)" <Li.Meng@....com>,
        "Karny, Wyes" <Wyes.Karny@....com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 05/13] cpufreq: amd-pstate: optimize driver working
 mode selection in amd_pstate_param()

On Mon, Dec 19, 2022 at 02:40:34PM +0800, Yuan, Perry wrote:
> There are some other amd pstate driver working mode to be supported.
> Here we use cppc_state var to indicate which mode is enabled.
> This change will help to simplify the the amd_pstate_param() to choose
> which mode used for the following driver registeration.
> 
> Signed-off-by: Perry Yuan <perry.yuan@....com>
> Signed-off-by: Wyes Karny <wyes.karny@....com>

The most of codes for this patch should be inherited by below patch:

https://lore.kernel.org/lkml/20221207154648.233759-2-wyes.karny@amd.com/

So I believe Wyes should be the author of this patch, please use git commit
--amend --author="Wyes Karny <wyes.karny@....com>" to update.

Thanks,
Ray

> ---
>  drivers/cpufreq/amd-pstate.c | 35 +++++++++++++++++++++++++++--------
>  include/linux/amd-pstate.h   | 29 +++++++++++++++++++++++++++++
>  2 files changed, 56 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index c17bd845f5fc..861a905f9324 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -60,7 +60,18 @@
>   * module parameter to be able to enable it manually for debugging.
>   */
>  static struct cpufreq_driver amd_pstate_driver;
> -static int cppc_load __initdata;
> +static int cppc_state = AMD_PSTATE_DISABLE;
> +
> +static inline int get_mode_idx_from_str(const char *str, size_t size)
> +{
> +	int i;
> +
> +	for (i=0; i < AMD_PSTATE_MAX; i++) {
> +		if (!strncmp(str, amd_pstate_mode_string[i], size))
> +			return i;
> +	}
> +	return -EINVAL;
> +}
>  
>  static inline int pstate_enable(bool enable)
>  {
> @@ -628,7 +639,7 @@ static int __init amd_pstate_init(void)
>  	 * enable the amd_pstate passive mode driver explicitly
>  	 * with amd_pstate=passive in kernel command line
>  	 */
> -	if (!cppc_load) {
> +	if (cppc_state == AMD_PSTATE_DISABLE) {
>  		pr_debug("driver load is disabled, boot with amd_pstate=passive to enable this\n");
>  		return -ENODEV;
>  	}
> @@ -671,16 +682,24 @@ device_initcall(amd_pstate_init);
>  
>  static int __init amd_pstate_param(char *str)
>  {
> +	size_t size;
> +	int mode_idx;
> +
>  	if (!str)
>  		return -EINVAL;
>  
> -	if (!strcmp(str, "disable")) {
> -		cppc_load = 0;
> -		pr_info("driver is explicitly disabled\n");
> -	} else if (!strcmp(str, "passive"))
> -		cppc_load = 1;
> +	size = strlen(str);
> +	mode_idx = get_mode_idx_from_str(str, size);
>  
> -	return 0;
> +	if (mode_idx >= AMD_PSTATE_DISABLE && mode_idx < AMD_PSTATE_MAX) {
> +		cppc_state = mode_idx;
> +		if (cppc_state == AMD_PSTATE_DISABLE)
> +			pr_info("driver is explicitly disabled\n");
> +
> +		return 0;
> +	}
> +
> +	return -EINVAL;
>  }
>  early_param("amd_pstate", amd_pstate_param);
>  
> diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> index 1c4b8659f171..922d05a13902 100644
> --- a/include/linux/amd-pstate.h
> +++ b/include/linux/amd-pstate.h
> @@ -74,4 +74,33 @@ struct amd_cpudata {
>  	bool	boost_supported;
>  };
>  
> +/**
> + * enum amd_pstate_mode - driver working mode of amd pstate
> + */
> +
> +enum amd_pstate_mode {
> +	/** @AMD_PSTATE_DISABLE: Driver mode is disabled */
> +	AMD_PSTATE_DISABLE = 0,
> +
> +	/** @AMD_PSTATE_PASSIVE: Drier mode is passive mode */
> +	AMD_PSTATE_PASSIVE = 1,
> +
> +	/** @AMD_PSTATE_ACTIVE: Driver mode is active mode */
> +	AMD_PSTATE_ACTIVE = 2,
> +
> +	/** @AMD_PSTATE_GUIDE: Driver mode is guided mode */
> +	AMD_PSTATE_GUIDE = 3,
> +
> +	/** @AMD_PSTATE_MAX */
> +	AMD_PSTATE_MAX = 4,
> +};
> +
> +static const char * const amd_pstate_mode_string[] = {
> +	[AMD_PSTATE_DISABLE]     = "disable",
> +	[AMD_PSTATE_PASSIVE]     = "passive",
> +	[AMD_PSTATE_ACTIVE]      = "active",
> +	[AMD_PSTATE_GUIDE]      = "guide",
> +	NULL,
> +};
> +
>  #endif /* _LINUX_AMD_PSTATE_H */
> -- 
> 2.34.1
>