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

["Justin He (Arm Technology China)" <Justin.He@arm.com>]

Hi Catalin
> -----Original Message-----
> From: Catalin Marinas <catalin.marinas@arm.com>
> Sent: 2019年9月20日 0:37
> To: Justin He (Arm Technology China) <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 (Arm Technology
> China) <Kaly.Xin@arm.com>
> Subject: Re: [PATCH v5 1/3] arm64: cpufeature: introduce helper
> cpu_has_hw_af()
>
> 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;
> }
>
Ok, thanks

--
Cheers,
Justin (Jia He)


> --
> Catalin
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