linux-kernel - Re: [PATCH 6/7] cpufreq: apple-soc: Set fallback transition latency to APPLE_DVFS_TRANSITION

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Message-ID: <3fab85df-371a-410b-a8de-40b6a62e9efe@arm.com>
Date: Wed, 11 Dec 2024 11:32:41 +0000
From: Christian Loehle <christian.loehle@....com>
To: Nick Chan <towinchenmi@...il.com>, Hector Martin <marcan@...can.st>,
 Sven Peter <sven@...npeter.dev>, Alyssa Rosenzweig <alyssa@...enzweig.io>,
 "Rafael J . Wysocki" <rafael@...nel.org>,
 Viresh Kumar <viresh.kumar@...aro.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, asahi@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/7] cpufreq: apple-soc: Set fallback transition latency
 to APPLE_DVFS_TRANSITION_TIMEOUT

On 12/11/24 11:19, Nick Chan wrote:
> The driver already assumes transitions will not take longer than
> APPLE_DVFS_TRANSITION_TIMEOUT in apple_soc_cpufreq_set_target(), so it
> makes little sense to set CPUFREQ_ETERNAL as the transition latency
> when the transistion latency is not given by the opp-table.
> 
> Signed-off-by: Nick Chan <towinchenmi@...il.com>
> ---
>  drivers/cpufreq/apple-soc-cpufreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/apple-soc-cpufreq.c b/drivers/cpufreq/apple-soc-cpufreq.c
> index 94e57f055a5f..0af36f911bea 100644
> --- a/drivers/cpufreq/apple-soc-cpufreq.c
> +++ b/drivers/cpufreq/apple-soc-cpufreq.c
> @@ -291,7 +291,7 @@ static int apple_soc_cpufreq_init(struct cpufreq_policy *policy)
>  
>  	transition_latency = dev_pm_opp_get_max_transition_latency(cpu_dev);
>  	if (!transition_latency)
> -		transition_latency = CPUFREQ_ETERNAL;
> +		transition_latency = APPLE_DVFS_TRANSITION_TIMEOUT;

transition_latency is in ns, APPLE_DVFS_TRANSITION_TIMEOUT in us.
LGTM otherwise.

>  
>  	policy->cpuinfo.transition_latency = transition_latency;
>  	policy->dvfs_possible_from_any_cpu = true;