[PATCH] LoongArch: Remove MIPS comment about cycle counter

[PATCH] LoongArch: Remove MIPS comment about cycle counter

[Jason A. Donenfeld]

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@zx2c4.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
-- 
2.35.1

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

[WANG Xuerui]

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@zx2c4.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@xen0n.name>

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

[Huacai Chen]

Hi, Xuerui and Jason,

Thank you very much, this will be applied later in the loongarch-fixes branch.

Huacai

On Sat, Jun 4, 2022 at 2:43 PM WANG Xuerui <kernel@xen0n.name> wrote:
>
> 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@zx2c4.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@xen0n.name>