linux-kernel - Re: [PATCH 04/19] cpufreq: amd: introduce a new amd pstate driver to support future processors

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Date:   Thu, 9 Sep 2021 17:03:54 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Huang Rui <ray.huang@....com>
Cc:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...nel.org>,
        linux-pm@...r.kernel.org, Deepak Sharma <deepak.sharma@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Nathan Fontenot <nathan.fontenot@....com>,
        Jinzhou Su <Jinzhou.Su@....com>,
        Xiaojian Du <Xiaojian.Du@....com>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 04/19] cpufreq: amd: introduce a new amd pstate driver to
 support future processors

On Wed, Sep 08, 2021 at 10:59:46PM +0800, Huang Rui wrote:

> +static int pstate_init_perf(struct amd_cpudata *cpudata)
> +{
> +	u64 cap1;
> +
> +	int ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
> +				     &cap1);
> +	if (ret)
> +		return ret;
> +
> +	/* Some AMD processors has specific power features that the cppc entry
> +	 * doesn't indicate the highest performance. It will introduce the
> +	 * feature in following days.
> +	 */

Wrong comment style; also imagine reading this comment half a year from
now...

> +	WRITE_ONCE(cpudata->highest_perf, amd_get_highest_perf());
> +
> +	WRITE_ONCE(cpudata->nominal_perf, CAP1_NOMINAL_PERF(cap1));
> +	WRITE_ONCE(cpudata->lowest_nonlinear_perf, CAP1_LOWNONLIN_PERF(cap1));
> +	WRITE_ONCE(cpudata->lowest_perf, CAP1_LOWEST_PERF(cap1));
> +
> +	return 0;
> +}