linux-kernel - Re: [PATCH 10/19] cpufreq: amd: add amd-pstate frequencies attributes

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Date:   Wed, 8 Sep 2021 13:13:41 -0500
From:   "Fontenot, Nathan" <Nathan.Fontenot@....com>
To:     Huang Rui <ray.huang@....com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...nel.org>,
        linux-pm@...r.kernel.org
Cc:     Deepak Sharma <deepak.sharma@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Jinzhou Su <Jinzhou.Su@....com>,
        Xiaojian Du <Xiaojian.Du@....com>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 10/19] cpufreq: amd: add amd-pstate frequencies attributes

On 9/8/2021 9:59 AM, Huang Rui wrote:
> Introduce sysfs attributes to get the different level processor
> frequencies.
> 
> Signed-off-by: Huang Rui <ray.huang@....com>
> ---
>  drivers/cpufreq/amd-pstate.c | 80 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 79 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 48dedd5af101..3c727a22cb69 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -577,16 +577,94 @@ static int amd_pstate_cpu_exit(struct cpufreq_policy *policy)
>  	return 0;
>  }
>  
> -static ssize_t show_is_amd_pstate_enabled(struct cpufreq_policy *policy,
> +/* Sysfs attributes */
> +
> +static ssize_t show_amd_pstate_max_freq(struct cpufreq_policy *policy,
>  					char *buf)
> +{
> +	int ret = 0, max_freq;
> +	struct amd_cpudata *cpudata;
> +
> +	cpudata = policy->driver_data;
> +
> +	max_freq = amd_get_max_freq(cpudata);
> +	if (max_freq < 0)
> +		return max_freq;
> +
> +	ret += sprintf(&buf[ret], "%u\n", max_freq);
> +
> +	return ret;

Here, and in the functions below, you could just do

	return sprintf(&buf[ret], "%u\n", max_freq);

and get rid of the intermediary 'ret' variable.

-Nathan

> +}
> +
> +static ssize_t show_amd_pstate_nominal_freq(struct cpufreq_policy *policy,
> +					    char *buf)
> +{
> +	int ret = 0, nominal_freq;
> +	struct amd_cpudata *cpudata;
> +
> +	cpudata = policy->driver_data;
> +
> +	nominal_freq = amd_get_nominal_freq(cpudata);
> +	if (nominal_freq < 0)
> +		return nominal_freq;
> +
> +	ret += sprintf(&buf[ret], "%u\n", nominal_freq);
> +
> +	return ret;
> +}
> +
> +static ssize_t
> +show_amd_pstate_lowest_nonlinear_freq(struct cpufreq_policy *policy, char *buf)
> +{
> +	int ret = 0, freq;
> +	struct amd_cpudata *cpudata;
> +
> +	cpudata = policy->driver_data;
> +
> +	freq = amd_get_lowest_nonlinear_freq(cpudata);
> +	if (freq < 0)
> +		return freq;
> +
> +	ret += sprintf(&buf[ret], "%u\n", freq);
> +
> +	return ret;
> +}
> +
> +static ssize_t show_amd_pstate_min_freq(struct cpufreq_policy *policy, char *buf)
> +{
> +	int ret = 0;
> +	int freq;
> +	struct amd_cpudata *cpudata;
> +
> +	cpudata = policy->driver_data;
> +
> +	freq = amd_get_min_freq(cpudata);
> +	if (freq < 0)
> +		return freq;
> +
> +	ret += sprintf(&buf[ret], "%u\n", freq);
> +
> +	return ret;
> +}
> +
> +static ssize_t show_is_amd_pstate_enabled(struct cpufreq_policy *policy,
> +					  char *buf)
>  {
>  	return sprintf(&buf[0], "%d\n", acpi_cpc_valid() ?  1 : 0);
>  }
>  
>  cpufreq_freq_attr_ro(is_amd_pstate_enabled);
> +cpufreq_freq_attr_ro(amd_pstate_max_freq);
> +cpufreq_freq_attr_ro(amd_pstate_nominal_freq);
> +cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
> +cpufreq_freq_attr_ro(amd_pstate_min_freq);
>  
>  static struct freq_attr *amd_pstate_attr[] = {
>  	&is_amd_pstate_enabled,
> +	&amd_pstate_max_freq,
> +	&amd_pstate_nominal_freq,
> +	&amd_pstate_lowest_nonlinear_freq,
> +	&amd_pstate_min_freq,
>  	NULL,
>  };
>  
> -- 
> 2.25.1
>