linux-kernel - Re: [PATCH 1/2] cpufreq: Introduce target min and max frequency hints

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Message-ID: <20201106100712.u336gbtblaxr2cit@vireshk-i7>
Date:   Fri, 6 Nov 2020 15:37:12 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Zhang Rui <rui.zhang@...el.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] cpufreq: Introduce target min and max frequency hints

On 05-11-20, 19:23, Rafael J. Wysocki wrote:
> Index: linux-pm/include/linux/cpufreq.h
> ===================================================================
> --- linux-pm.orig/include/linux/cpufreq.h
> +++ linux-pm/include/linux/cpufreq.h
> @@ -63,6 +63,8 @@ struct cpufreq_policy {
>  
>  	unsigned int		min;    /* in kHz */
>  	unsigned int		max;    /* in kHz */
> +	unsigned int		target_min; /* in kHz */
> +	unsigned int		target_max; /* in kHz */
>  	unsigned int		cur;    /* in kHz, only needed if cpufreq
>  					 * governors are used */
>  	unsigned int		suspend_freq; /* freq to set during suspend */

Rafael, honestly speaking I didn't like this patch very much. We need
to fix a very specific problem with the intel-pstate driver when it is
used with powersave/performance governor to make sure the hard limits
are enforced. And this is something which no one else may face as
well.

What about doing something like this instead in the intel_pstate
driver only to get this fixed ?

        if (!strcmp(policy->governor->name, "powersave") ||
            !strcmp(policy->governor->name, "performance"))
                hard-limit-to-be-enforced;

This would be a much simpler and contained approach IMHO.

-- 
viresh