linux-kernel - Re: [PATCH v19 05/11] perf: arm_v7_pmu: Don't disable counter in (armv7|krait_|scorpion_)pmu_enable

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Message-ID: <9a4e16af-b5b9-406f-8f9f-4d395a14a61c@arm.com>
Date: Mon, 3 Feb 2025 12:24:42 +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 05/11] perf: arm_v7_pmu: Don't disable counter in
 (armv7|krait_|scorpion_)pmu_enable_event()



On 2/3/25 06:12, Rob Herring (Arm) wrote:
> Currently (armv7|krait_|scorpion_)pmu_enable_event() start 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 *_enable_event() is called.
> 
> Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
> ---
>  drivers/perf/arm_v7_pmu.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/perf/arm_v7_pmu.c b/drivers/perf/arm_v7_pmu.c
> index 7fa88e3b64e0..17831e1920bd 100644
> --- a/drivers/perf/arm_v7_pmu.c
> +++ b/drivers/perf/arm_v7_pmu.c
> @@ -857,8 +857,6 @@ static void armv7pmu_enable_event(struct perf_event *event)
>  		return;
>  	}
>  
> -	armv7_pmnc_disable_counter(idx);
> -
>  	/*
>  	 * Set event (if destined for PMNx counters)
>  	 * We only need to set the event for the cycle counter if we
> @@ -1450,8 +1448,6 @@ static void krait_pmu_enable_event(struct perf_event *event)
>  	struct hw_perf_event *hwc = &event->hw;
>  	int idx = hwc->idx;
>  
> -	armv7_pmnc_disable_counter(idx);
> -
>  	/*
>  	 * Set event (if destined for PMNx counters)
>  	 * We set the event for the cycle counter because we
> @@ -1762,8 +1758,6 @@ static void scorpion_pmu_enable_event(struct perf_event *event)
>  	struct hw_perf_event *hwc = &event->hw;
>  	int idx = hwc->idx;
>  
> -	armv7_pmnc_disable_counter(idx);
> -
>  	/*
>  	 * Set event (if destined for PMNx counters)
>  	 * We don't set the event for the cycle counter because we
> 

LGTM

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