linux-kernel - Re: [PATCH] drivers: perf: use us_to

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Message-ID: <2c6d68da-fd1a-4b59-8bfc-5e1c66ceaebe@arm.com>
Date: Wed, 27 Aug 2025 15:05:58 +0100
From: Robin Murphy <robin.murphy@....com>
To: Mark Rutland <mark.rutland@....com>, Xichao Zhao <zhao.xichao@...o.com>
Cc: will@...nel.org, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] drivers: perf: use us_to_ktime() where appropriate

On 27/08/2025 10:36 am, Mark Rutland wrote:
> [adding Robin and LAKML]
> 
> On Wed, Aug 13, 2025 at 04:32:57PM +0800, Xichao Zhao wrote:
>> The arm_ccn_pmu_poll_period_us are more suitable for using
>> the us_to_ktime(). This can make the code more concise and
>> enhance readability.
>>
>> Signed-off-by: Xichao Zhao <zhao.xichao@...o.com>
> 
> Superficially this looks fine to me, so:
> 
> Acked-by: Mark Rutland <mark.rutland@....com>
> 
> Will, I assume that (if no-one complains) you'll pick this up when
> queueing PMU patches.

Yup, the new helper looks entirely appropriate here. We could perhaps 
take this opportunity to drop the unnecessary cast as well though, since 
automatic promotion from unsigned int to u64 is perfectly well-defined 
and unsurprising.

Thanks,
Robin.

> 
> Mark.
> 
>> ---
>>   drivers/perf/arm-ccn.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/perf/arm-ccn.c b/drivers/perf/arm-ccn.c
>> index 1a0d0e1a2263..8af3563fdf60 100644
>> --- a/drivers/perf/arm-ccn.c
>> +++ b/drivers/perf/arm-ccn.c
>> @@ -565,7 +565,7 @@ module_param_named(pmu_poll_period_us, arm_ccn_pmu_poll_period_us, uint,
>>   
>>   static ktime_t arm_ccn_pmu_timer_period(void)
>>   {
>> -	return ns_to_ktime((u64)arm_ccn_pmu_poll_period_us * 1000);
>> +	return us_to_ktime((u64)arm_ccn_pmu_poll_period_us);
>>   }
>>   
>>   
>> -- 
>> 2.34.1
>>