Re: [RESEND PATCH v2 2/2] arm64/watchdog_hld: Add a cpufreq notifier for update watchdog thresh

[Will Deacon <will@kernel.org>]

On Thu, Jun 19, 2025 at 07:48:05PM +0800, Yicong Yang wrote:
> From: Yicong Yang <yangyicong@hisilicon.com>
> 
> arm64 depends on the cpufreq driver to gain the maximum cpu frequency
> to convert the watchdog_thresh to perf event period. cpufreq drivers
> like cppc_cpufreq will be initialized lately after the initializing of
> the hard lockup detector so just use a safe cpufreq which will be
> inaccurency. Use a cpufreq notifier to adjust the event's period to
> a more accurate one.
> 
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> ---
>  arch/arm64/kernel/watchdog_hld.c | 58 ++++++++++++++++++++++++++++++++
>  1 file changed, 58 insertions(+)
> 
> diff --git a/arch/arm64/kernel/watchdog_hld.c b/arch/arm64/kernel/watchdog_hld.c
> index dcd25322127c..e55548cb26df 100644
> --- a/arch/arm64/kernel/watchdog_hld.c
> +++ b/arch/arm64/kernel/watchdog_hld.c
> @@ -34,3 +34,61 @@ bool __init arch_perf_nmi_is_available(void)
>  	 */
>  	return arm_pmu_irq_is_nmi();
>  }
> +
> +static int watchdog_perf_update_period(void *data)
> +{
> +	int cpu = raw_smp_processor_id();

Why raw?

Will