linux-kernel - Re: [PATCH v19 03/11] perf: arm_pmuv3: Don't disable counter in armv8pmu_enable

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Message-ID: <8584f5cc-70b0-46a0-9582-8d7b4d491ba6@arm.com>
Date: Mon, 3 Feb 2025 12:08:35 +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 03/11] perf: arm_pmuv3: Don't disable counter in
 armv8pmu_enable_event()

On 2/3/25 06:12, Rob Herring (Arm) wrote:
> From: Mark Rutland <mark.rutland@....com>
> 
> Currently armv8pmu_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
> armv8pmu_enable_event() is called.
Makes sense.

> 
> Remove the redundant call to armv8pmu_disable_event_counter(). At the
> same time, remove the comment immeditately above as everything it says

s/immeditately/immediately

> is obvious from the function names below.

But should this comment drop change be folded into the next patch which
exclusively drops all obviously redundant disable/enable comments.

> 
> Signed-off-by: Mark Rutland <mark.rutland@....com>
> Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
> ---
>  drivers/perf/arm_pmuv3.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
> index 9ebc950559c0..5406b9ca591a 100644
> --- a/drivers/perf/arm_pmuv3.c
> +++ b/drivers/perf/arm_pmuv3.c
> @@ -795,11 +795,6 @@ static void armv8pmu_enable_user_access(struct arm_pmu *cpu_pmu)
>  
>  static void armv8pmu_enable_event(struct perf_event *event)
>  {
> -	/*
> -	 * Enable counter and interrupt, and set the counter to count
> -	 * the event that we're interested in.
> -	 */
> -	armv8pmu_disable_event_counter(event);
>  	armv8pmu_write_event_type(event);
>  	armv8pmu_enable_event_irq(event);
>  	armv8pmu_enable_event_counter(event);
> 

Otherwise LGTM.

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