linux-kernel - Re: [PATCH] LoongArch: Remove MIPS comment about cycle counter

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Message-ID: <18ffcffb-1335-03ec-ac34-f75264460e13@xen0n.name>
Date:   Sat, 4 Jun 2022 14:43:02 +0800
From:   WANG Xuerui <kernel@...0n.name>
To:     "Jason A. Donenfeld" <Jason@...c4.com>, chenhuacai@...nel.org,
        kernel@...0n.name, linux-kernel@...r.kernel.org, arnd@...db.de
Subject: Re: [PATCH] LoongArch: Remove MIPS comment about cycle counter

On 6/4/22 14:35, Jason A. Donenfeld wrote:
> This comment block was taken originally from the MIPS architecture code,
> where indeed there are particular assumptions one can make regarding SMP
> and !SMP and cycle counters. On LoongArch, however, the rdtime family of
> functions is always available. As Xuerui wrote:
>
>      The rdtime family of instructions is in fact guaranteed to be
>      available on LoongArch; LoongArch's subsets all contain them, even
>      the 32-bit "Primary" subset intended for university teaching -- they
>      provide the rdtimeh.w and rdtimel.w pair of instructions that access
>      the same 64-bit counter.
>
> So this commit simply removes the incorrect comment block.
>
> Link: https://lore.kernel.org/lkml/e78940bc-9be2-2fe7-026f-9e64a1416c9f@xen0n.name/
> Fixes: b738c106f735 ("LoongArch: Add other common headers")
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
> ---
>   arch/loongarch/include/asm/timex.h | 7 -------
>   1 file changed, 7 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/timex.h b/arch/loongarch/include/asm/timex.h
> index d3ed99a4fdbd..fb41e9e7a222 100644
> --- a/arch/loongarch/include/asm/timex.h
> +++ b/arch/loongarch/include/asm/timex.h
> @@ -12,13 +12,6 @@
>   #include <asm/cpu.h>
>   #include <asm/cpu-features.h>
>   
> -/*
> - * Standard way to access the cycle counter.
> - * Currently only used on SMP for scheduling.
> - *
> - * We know that all SMP capable CPUs have cycle counters.
> - */
> -
>   typedef unsigned long cycles_t;
>   
>   #define get_cycles get_cycles

Just as previously discussed. Thanks for the quick fixup!

Reviewed-by: WANG Xuerui <git@...0n.name>