Re: [PATCH] perf: arm_cspmu: Don't touch interrupt registers if no interrupt was assigned

[Robin Murphy <robin.murphy@arm.com>]

On 2024-03-07 7:31 pm, Ilkka Koskinen wrote:
> The driver enabled and disabled interrupts even if no interrupt was
> assigned to the device.

Why's that a concern - if the interrupt isn't routed anywhere, surely it 
makes no difference what happens at the source end?

Thanks,
Robin.

> Signed-off-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
> ---
>   drivers/perf/arm_cspmu/arm_cspmu.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
> index 50b89b989ce7..2cbdb5dcb6ff 100644
> --- a/drivers/perf/arm_cspmu/arm_cspmu.c
> +++ b/drivers/perf/arm_cspmu/arm_cspmu.c
> @@ -795,7 +795,8 @@ static void arm_cspmu_enable_counter(struct arm_cspmu *cspmu, int idx)
>   	inten_off = PMINTENSET + (4 * reg_id);
>   	cnten_off = PMCNTENSET + (4 * reg_id);
>   
> -	writel(BIT(reg_bit), cspmu->base0 + inten_off);
> +	if (cspmu->irq)
> +		writel(BIT(reg_bit), cspmu->base0 + inten_off);
>   	writel(BIT(reg_bit), cspmu->base0 + cnten_off);
>   }
>   
> @@ -810,7 +811,8 @@ static void arm_cspmu_disable_counter(struct arm_cspmu *cspmu, int idx)
>   	cnten_off = PMCNTENCLR + (4 * reg_id);
>   
>   	writel(BIT(reg_bit), cspmu->base0 + cnten_off);
> -	writel(BIT(reg_bit), cspmu->base0 + inten_off);
> +	if (cspmu->irq)
> +		writel(BIT(reg_bit), cspmu->base0 + inten_off);
>   }
>   
>   static void arm_cspmu_event_update(struct perf_event *event)