linux-kernel - Re: [PATCH v2 16/22] arm64/debug: Make use of the system wide safe value

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Message-ID: <20151008111128.GH17192@e104818-lin.cambridge.arm.com>
Date:	Thu, 8 Oct 2015 12:11:28 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	"Suzuki K. Poulose" <suzuki.poulose@....com>
Cc:	linux-arm-kernel@...ts.infradead.org, mark.rutland@....com,
	Vladimir.Murzin@....com, steve.capper@...aro.org,
	ard.biesheuvel@...aro.org, marc.zyngier@....com,
	will.deacon@....com, linux-kernel@...r.kernel.org,
	edward.nevill@...aro.org, aph@...hat.com, james.morse@....com,
	andre.przywara@....com, dave.martin@....com
Subject: Re: [PATCH v2 16/22] arm64/debug: Make use of the system wide safe
 value

On Mon, Oct 05, 2015 at 06:02:05PM +0100, Suzuki K. Poulose wrote:
> @@ -137,13 +138,17 @@ extern struct pmu perf_ops_bp;
>  /* Determine number of BRP registers available. */
>  static inline int get_num_brps(void)
>  {
> -	return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1;
> +	return 1 +
> +		cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1),
> +						ID_AA64DFR0_BRPS_SHIFT);
>  }

cpuid_feature_extract_field() is fine but we should we bother with
read_system_reg vs just read_cpuid?

Similar question for patch 17/22.

-- 
Catalin
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