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

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Message-ID: <alpine.LNX.2.20.13.2105130130590.10864@monopod.intra.ispras.ru>
Date:   Thu, 13 May 2021 01:34:22 +0300 (MSK)
From:   Alexander Monakov <amonakov@...ras.ru>
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

On Sun, 25 Apr 2021, Huang Rui 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:

The commit message says '255', but the code:

> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -1170,3 +1170,19 @@ void set_dr_addr_mask(unsigned long mask, int dr)
>  		break;
>  	}
>  }
> +
> +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;
> +
> +	return 225;
> +}

says 225? This is probably a typo? In any case they are out of sync.

Alexander