linux-kernel - Re: [PATCH 1/2][v2] cpufreq: intel_pstate: Add parameter to get guarantee frequency

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Message-ID: <20210112032902.GB28619@chenyu-office.sh.intel.com>
Date:   Tue, 12 Jan 2021 11:29:02 +0800
From:   Chen Yu <yu.c.chen@...el.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Wendy Wang <wendy.wang@...el.com>
Subject: Re: [PATCH 1/2][v2] cpufreq: intel_pstate: Add parameter to get
 guarantee frequency

On Mon, Jan 11, 2021 at 01:44:09PM +0100, Rafael J. Wysocki wrote:
> On Mon, Jan 11, 2021 at 8:40 AM Chen Yu <yu.c.chen@...el.com> wrote:
> >
> > Add input parameter to receive guarantee pstate from intel_pstate_get_hwp_max()
> > for later use.
> 
> I'm not a fan of this change, because the new argument will only be
> needed in one place where intel_pstate_get_hwp_max() and it requires
> adding redundant local vars and pointless updates elsewhere.
> 
> Besides, in intel_pstate_get_cpu_pstates() you can do something like
> this after calling intel_pstate_get_hwp_max():
> 
> cpu->pstate.max_pstate = HWP_GUARANTEED_PERF(READ_ONCE(cpu->hwp_cap_cached));
> cpu->pstate.max_freq = cpu->pstate.max_pstate * cpu->pstate.scaling;
Okay, will do in next version.

Thanks,
Chenyu