linux-kernel - Re: [PATCH 2/2] powercap/rapl: add support for denverton

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Message-ID: <574E0DF2.2010408@intel.com>
Date:	Tue, 31 May 2016 15:19:30 -0700
From:	Dave Hansen <dave.hansen@...el.com>
To:	Jacob Pan <jacob.jun.pan@...ux.intel.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM <linux-pm@...r.kernel.org>,
	Rafael Wysocki <rafael.j.wysocki@...el.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	the arch/x86 maintainers <x86@...nel.org>
Subject: Re: [PATCH 2/2] powercap/rapl: add support for denverton

On 05/31/2016 01:41 PM, Jacob Pan wrote:
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -1137,6 +1137,7 @@ static const struct x86_cpu_id rapl_ids[] __initconst = {
>  	RAPL_CPU(0x57, rapl_defaults_hsw_server),/* Knights Landing */
>  	RAPL_CPU(0x8E, rapl_defaults_core),/* Kabylake */
>  	RAPL_CPU(0x9E, rapl_defaults_core),/* Kabylake */
> +	RAPL_CPU(0x5F, rapl_defaults_core),/* Denverton micro server */
>  	{}
>  };

Not to derail this individual patch... but do we really want to continue
open-coding CPU model/family combos all over arch/x86?

For instance, arch/x86/events/intel/core.c has:

>         case 142: /* 14nm Kabylake Mobile */
>         case 158: /* 14nm Kabylake Desktop */
>         case 78: /* 14nm Skylake Mobile */
>         case 94: /* 14nm Skylake Desktop */
>         case 85: /* 14nm Skylake Server */

Which duplicates the two Kabylake family numbers from the RAPL_CPU()
context above (just in decimal instead of hex).

Should we just start sticking these things in a header like:

#define X86_INTEL_FAMILY_KABYLAKE1 	0x8E
#define X86_INTEL_FAMILY_KABYLAKE2	0x9E
#define X86_INTEL_FAMILY_DENVERTON 	0x5F

So we have this:

	RAPL_CPU(X86_INTEL_FAMILY_DENVERTON, rapl_defaults_core),

instead of having to explain our magic number in a comment.