linux-kernel - Re: [PATCH 2/2] cpufreq: cppc: cppc_cpufreq_get

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Date:   Wed, 16 Aug 2023 09:06:14 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Liao Chang <liaochang1@...wei.com>
Cc:     rafael@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] cpufreq: cppc: cppc_cpufreq_get_rate() returns zero
 in all error cases.

On 15-08-23, 09:40, Liao Chang wrote:
> The cpufreq framework used to use the zero of return value to reflect
> the cppc_cpufreq_get_rate() had failed to get current frequecy and treat
> all positive integer to be succeed. Since cppc_get_perf_ctrs() returns a
> negative integer in error case, so it is better to convert the value to
> zero as the return value of cppc_cpufreq_get_rate().
> 
> Signed-off-by: Liao Chang <liaochang1@...wei.com>
> ---
>  drivers/cpufreq/cppc_cpufreq.c | 4 ++--
>  include/linux/cpufreq.h        | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> index 796bc3e19f77..1cdef2da1ea4 100644
> --- a/drivers/cpufreq/cppc_cpufreq.c
> +++ b/drivers/cpufreq/cppc_cpufreq.c
> @@ -854,13 +854,13 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpu)
>  
>  	ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t0);
>  	if (ret)
> -		return ret;
> +		return 0;
>  
>  	udelay(2); /* 2usec delay between sampling */
>  
>  	ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t1);
>  	if (ret)
> -		return ret;
> +		return 0;
>  
>  	delivered_perf = cppc_perf_from_fbctrs(cpu_data, &fb_ctrs_t0,
>  					       &fb_ctrs_t1);
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 172ff51c1b2a..99da27466b8f 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -370,7 +370,7 @@ struct cpufreq_driver {
>  	int		(*target_intermediate)(struct cpufreq_policy *policy,
>  					       unsigned int index);
>  
> -	/* should be defined, if possible */
> +	/* should be defined, if possible, return 0 on error */
>  	unsigned int	(*get)(unsigned int cpu);
>  
>  	/* Called to update policy limits on firmware notifications. */

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh