linux-kernel - Re: [PATCH 3/5] arm64: refactor delay() to enable polling for value

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Message-ID: <efd92a03-f5a9-ba9b-338f-b9a5ad93174f@gentwo.org>
Date: Tue, 5 Nov 2024 11:42:58 -0800 (PST)
From: "Christoph Lameter (Ampere)" <cl@...two.org>
To: Haris Okanovic <harisokn@...zon.com>
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Subject: Re: [PATCH 3/5] arm64: refactor delay() to enable polling for
 value

On Tue, 5 Nov 2024, Haris Okanovic wrote:

> -#define USECS_TO_CYCLES(time_usecs)			\
> -	xloops_to_cycles((time_usecs) * 0x10C7UL)
> -
> -static inline unsigned long xloops_to_cycles(unsigned long xloops)
> +static inline u64 xloops_to_cycles(u64 xloops)
>  {
>  	return (xloops * loops_per_jiffy * HZ) >> 32;
>  }
>
> -void __delay(unsigned long cycles)
> +#define USECS_TO_XLOOPS(time_usecs) \
> +	((time_usecs) * 0x10C7UL)
> +
> +#define USECS_TO_CYCLES(time_usecs) \
> +	xloops_to_cycles(USECS_TO_XLOOPS(time_usecs))
> +


> +#define NSECS_TO_XLOOPS(time_nsecs) \
> +	((time_nsecs) * 0x10C7UL)

The constant here is the same value as for microseconds. If I remember
correctly its 5UL for nanoseconds.