Re: [PATCH 2/2] cpufreq: arm_scmi: Set fast_switch_possible conditionally

From: Viresh Kumar <viresh.kumar@linaro.org>
To: Nicola Mazzucato <nicola.mazzucato@arm.com>
Cc: linux-kernel@vger.kernel.org, sudeep.holla@arm.com,
	rjw@rjwysocki.net, linux-arm-kernel@lists.infradead.org,
	linux-pm@vger.kernel.org, lukasz.luba@arm.com
Subject: Re: [PATCH 2/2] cpufreq: arm_scmi: Set fast_switch_possible conditionally
Date: Thu, 18 Jun 2020 15:24:29 +0530	[thread overview]
Message-ID: <20200618095429.tj3ddquy5m2q367e@vireshk-i7> (raw)
In-Reply-To: <20200617094332.8391-2-nicola.mazzucato@arm.com>

On 17-06-20, 10:43, Nicola Mazzucato wrote:
> Currently the fast_switch_possible flag is set unconditionally
> to true. Based on this, schedutil does not create a
> thread for frequency switching and would always use the
> fast switch path.
> However, if the platform does not support frequency
> fast switch, this may cause the governor to attempt an
> operation that is not supported by the platform.
> 
> Fix this by correctly retrieve the fast_switch capability
> from the driver which knows if the platform can support
> this feature.
> 
> Suggested-by: Lukasz Luba <lukasz.luba@arm.com>
> Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
> ---
>  drivers/cpufreq/scmi-cpufreq.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index 61623e2ff149..1cf688fcb56b 100644
> --- a/drivers/cpufreq/scmi-cpufreq.c
> +++ b/drivers/cpufreq/scmi-cpufreq.c
> @@ -198,7 +198,8 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>  
>  	policy->cpuinfo.transition_latency = latency;
>  
> -	policy->fast_switch_possible = true;
> +	policy->fast_switch_possible =
> +		handle->perf_ops->fast_switch_possible(handle, cpu_dev);
>  
>  	em_register_perf_domain(policy->cpus, nr_opp, &em_cb);

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

-- 
viresh