linux-kernel - Re: [RFC PATCH 4/9] opp: core: Don't warn if required OPP device does not exist

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Date:   Thu, 14 Oct 2021 12:26:36 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Hector Martin <marcan@...can.st>
Cc:     Sibi Sankar <sibis@...eaurora.org>,
        Saravana Kannan <saravanak@...gle.com>,
        linux-arm-kernel@...ts.infradead.org,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Sven Peter <sven@...npeter.dev>, Marc Zyngier <maz@...nel.org>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Catalin Marinas <catalin.marinas@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 4/9] opp: core: Don't warn if required OPP device
 does not exist

On 14-10-21, 15:52, Hector Martin wrote:
> The CPU devices aren't attached to their genpd, so the required OPP
> transition fails with the same error.
> 
> However, this was easier to fix than I expected. With this patch to
> cpufreq-dt, it all works properly, and I can drop the parent genpd
> from the clock node and related handling. Thoughts?
> 
> commit c4f88743374c1f4678ee7f17fb6cae30ded9ed59
> Author: Hector Martin <marcan@...can.st>
> Date:   Thu Oct 14 15:47:45 2021 +0900
> 
>     cpufreq: dt: Attach CPU devices to power domains
>     This allows the required-opps mechanism to work for CPU OPP tables,
>     triggering specific OPP levels in a parent power domain.
>     Signed-off-by: Hector Martin <marcan@...can.st>
> 
> diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
> index 8fcaba541539..5b22846b557d 100644
> --- a/drivers/cpufreq/cpufreq-dt.c
> +++ b/drivers/cpufreq/cpufreq-dt.c
> @@ -16,6 +16,7 @@
>  #include <linux/list.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/pm_domain.h>
>  #include <linux/pm_opp.h>
>  #include <linux/platform_device.h>
>  #include <linux/regulator/consumer.h>
> @@ -264,6 +265,16 @@ static int dt_cpufreq_early_init(struct device *dev, int cpu)
>  		goto out;
>  	}
> +	/*
> +	 * Attach the CPU device to its genpd domain (if any), to allow OPP
> +	 * dependencies to be satisfied.
> +	 */
> +	ret = genpd_dev_pm_attach(cpu_dev);
> +	if (ret <= 0) {
> +		dev_err(cpu_dev, "Failed to attach CPU device to genpd\n");
> +		goto out;
> +	}
> +

Other platform do this from some other place I think.

Ulf, where should this code be moved ? cpu-clk driver ?

-- 
viresh