Re: [PATCH v5 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af()

From: Catalin Marinas <catalin.marinas@arm.com>
To: Jia He <justin.he@arm.com>
Cc: "Will Deacon" <will@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"James Morse" <james.morse@arm.com>,
	"Marc Zyngier" <maz@kernel.org>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	"Suzuki Poulose" <Suzuki.Poulose@arm.com>,
	"Punit Agrawal" <punitagrawal@gmail.com>,
	"Anshuman Khandual" <anshuman.khandual@arm.com>,
	"Alex Van Brunt" <avanbrunt@nvidia.com>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Ralph Campbell" <rcampbell@nvidia.com>,
	hejianet@gmail.com, "Kaly Xin" <Kaly.Xin@arm.com>
Subject: Re: [PATCH v5 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af()
Date: Thu, 19 Sep 2019 17:36:44 +0100	[thread overview]
Message-ID: <20190919163644.GD6472@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190919161204.142796-2-justin.he@arm.com>

On Fri, Sep 20, 2019 at 12:12:02AM +0800, Jia He wrote:
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index b1fdc486aed8..fb0e9425d286 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1141,6 +1141,16 @@ static bool has_hw_dbm(const struct arm64_cpu_capabilities *cap,
>  	return true;
>  }
>  
> +/* Decouple AF from AFDBM. */
> +bool cpu_has_hw_af(void)
> +{
> +	return (read_cpuid(ID_AA64MMFR1_EL1) & 0xf);
> +}
> +#else /* CONFIG_ARM64_HW_AFDBM */
> +bool cpu_has_hw_af(void)
> +{
> +	return false;
> +}
>  #endif

Please place this function in cpufeature.h directly, no need for an
additional function call. Something like:

static inline bool cpu_has_hw_af(void)
{
	if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM))
		return read_cpuid(ID_AA64MMFR1_EL1) & 0xf;
	return false;
}

-- 
Catalin