linux-kernel - Re: [PATCH v19 06/11] perf: apple_m1: Don't disable counter in m1_pmu_enable

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Message-ID: <e63478e7-de74-4228-9b75-a26a9a3dd294@arm.com>
Date: Mon, 3 Feb 2025 13:40:20 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: "Rob Herring (Arm)" <robh@...nel.org>, Will Deacon <will@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Catalin Marinas <catalin.marinas@....com>, Jonathan Corbet <corbet@....net>,
 Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
 Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>,
 Zenghui Yu <yuzenghui@...wei.com>, James Clark <james.clark@...aro.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 kvmarm@...ts.linux.dev
Subject: Re: [PATCH v19 06/11] perf: apple_m1: Don't disable counter in
 m1_pmu_enable_event()



On 2/3/25 06:13, Rob Herring (Arm) wrote:
> Currently m1_pmu_enable_event() starts by disabling the event counter
> it has been asked to enable. This should not be necessary as the
> counter (and the PMU as a whole) should not be active when
> m1_pmu_enable_event() is called.
> 
> Cc: Marc Zyngier <maz@...nel.org>
> Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
> ---
>  drivers/perf/apple_m1_cpu_pmu.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/perf/apple_m1_cpu_pmu.c b/drivers/perf/apple_m1_cpu_pmu.c
> index 06fd317529fc..39349ecec3c1 100644
> --- a/drivers/perf/apple_m1_cpu_pmu.c
> +++ b/drivers/perf/apple_m1_cpu_pmu.c
> @@ -396,10 +396,6 @@ static void m1_pmu_enable_event(struct perf_event *event)
>  	user = event->hw.config_base & M1_PMU_CFG_COUNT_USER;
>  	kernel = event->hw.config_base & M1_PMU_CFG_COUNT_KERNEL;
>  
> -	m1_pmu_disable_counter_interrupt(event->hw.idx);
> -	m1_pmu_disable_counter(event->hw.idx);
> -	isb();
> -
>  	m1_pmu_configure_counter(event->hw.idx, evt, user, kernel);
>  	m1_pmu_enable_counter(event->hw.idx);
>  	m1_pmu_enable_counter_interrupt(event->hw.idx);
> 

Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>