Re: [PATCH v4 1/2] watchdog: move arm64 watchdog_hld into common code

[Will Deacon <will@kernel.org>]

On Tue, Oct 14, 2025 at 11:14:24AM +0800, Yunhui Cui wrote:
> @@ -306,3 +307,85 @@ void __init hardlockup_config_perf_event(const char *str)
>  	wd_hw_attr.type = PERF_TYPE_RAW;
>  	wd_hw_attr.config = config;
>  }
> +
> +#ifdef CONFIG_WATCHDOG_PERF_ADJUST_PERIOD
> +/*
> + * Safe maximum CPU frequency in case a particular platform doesn't implement
> + * cpufreq driver. Although, architecture doesn't put any restrictions on
> + * maximum frequency but 5 GHz seems to be safe maximum given the available
> + * CPUs in the market which are clocked much less than 5 GHz. On the other
> + * hand, we can't make it much higher as it would lead to a large hard-lockup
> + * detection timeout on parts which are running slower (eg. 1GHz on
> + * Developerbox) and doesn't possess a cpufreq driver.
> + */
> +#define SAFE_MAX_CPU_FREQ	5000000000UL // 5 GHz
> +__weak u64 hw_nmi_get_sample_period(int watchdog_thresh)
> +{
> +	unsigned int cpu = smp_processor_id();
> +	unsigned long max_cpu_freq;
> +
> +	max_cpu_freq = cpufreq_get_hw_max_freq(cpu) * 1000UL;
> +	if (!max_cpu_freq)
> +		max_cpu_freq = SAFE_MAX_CPU_FREQ;
> +
> +	return (u64)max_cpu_freq * watchdog_thresh;
> +}

Why does this function become __weak? Neither arm64 nor riscv override
it afaict.

Will