linux-kernel - Re: [PATCH v4] x86, sched: Fix the AMD CPPC maximum perf on some specific generations

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Message-ID: <YJwpVA2UHGBuag0w@gmail.com>
Date:   Wed, 12 May 2021 21:15:32 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Huang Rui <ray.huang@....com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alex Deucher <alexander.deucher@....com>,
        Jason Bagavatsingham <jason.bagavatsingham@...il.com>,
        "Pierre-Loup A . Griffais" <pgriffais@...vesoftware.com>,
        Nathan Fontenot <nathan.fontenot@....com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Borislav Petkov <bp@...e.de>, x86@...nel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v4] x86, sched: Fix the AMD CPPC maximum perf on some
 specific generations


* Huang Rui <ray.huang@....com> wrote:

> Some AMD Ryzen generations has different calculation method on maximum
> perf. 255 is not for all asics, some specific generations should use 166
> as the maximum perf. Otherwise, it will report incorrect frequency value
> like below:
> 
> ~ → lscpu | grep MHz
> CPU MHz:                         3400.000
> CPU max MHz:                     7228.3198
> CPU min MHz:                     2200.0000

It would have been useful to also quote the 'after' part.

> +u32 amd_get_highest_perf(void)
> +{
> +	struct cpuinfo_x86 *c = &boot_cpu_data;
> +
> +	if (c->x86 == 0x17 && ((c->x86_model >= 0x30 && c->x86_model < 0x40) ||
> +			       (c->x86_model >= 0x70 && c->x86_model < 0x80)))
> +	    return 166;
> +
> +	if (c->x86 == 0x19 && ((c->x86_model >= 0x20 && c->x86_model < 0x30) ||
> +			       (c->x86_model >= 0x40 && c->x86_model < 0x70)))
> +	    return 166;

I fixed these stray 4-space tabs.

Looks good otherwise - queued up in tip:sched/urgent.

Thanks,

	Ingo