linux-kernel - Re: [PATCH v6 12/15] MIPS: JZ4770: Work around config2 misreporting associativity

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Date:   Wed, 10 Jan 2018 22:52:16 +0000
From:   James Hogan <james.hogan@...s.com>
To:     Paul Cercueil <paul@...pouillou.net>
CC:     Ralf Baechle <ralf@...ux-mips.org>,
        Maarten ter Huurne <maarten@...ewalker.org>,
        Paul Burton <paul.burton@...s.com>,
        <linux-kernel@...r.kernel.org>, <linux-mips@...ux-mips.org>
Subject: Re: [PATCH v6 12/15] MIPS: JZ4770: Work around config2 misreporting
 associativity

On Fri, Jan 05, 2018 at 07:25:10PM +0100, Paul Cercueil wrote:
> From: Maarten ter Huurne <maarten@...ewalker.org>
> 
> According to config2, the associativity would be 5-ways, but the
> documentation states 4-ways, which also matches the documented
> L2 cache size of 256 kB.
> 
> Signed-off-by: Maarten ter Huurne <maarten@...ewalker.org>

Hehe, nice

Reviewed-by: James Hogan <jhogan@...nel.org>

Cheers
James

> ---
>  arch/mips/mm/sc-mips.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
>  v2: No change
>  v3: No change
>  v4: Rebased on top of Linux 4.15-rc5
>  v5: No change
>  v6: No change
> 
> diff --git a/arch/mips/mm/sc-mips.c b/arch/mips/mm/sc-mips.c
> index 548acb7f8557..394673991bab 100644
> --- a/arch/mips/mm/sc-mips.c
> +++ b/arch/mips/mm/sc-mips.c
> @@ -16,6 +16,7 @@
>  #include <asm/mmu_context.h>
>  #include <asm/r4kcache.h>
>  #include <asm/mips-cps.h>
> +#include <asm/bootinfo.h>
>  
>  /*
>   * MIPS32/MIPS64 L2 cache handling
> @@ -220,6 +221,14 @@ static inline int __init mips_sc_probe(void)
>  	else
>  		return 0;
>  
> +	/*
> +	 * According to config2 it would be 5-ways, but that is contradicted
> +	 * by all documentation.
> +	 */
> +	if (current_cpu_type() == CPU_JZRISC &&
> +				mips_machtype == MACH_INGENIC_JZ4770)
> +		c->scache.ways = 4;
> +
>  	c->scache.waysize = c->scache.sets * c->scache.linesz;
>  	c->scache.waybit = __ffs(c->scache.waysize);
>  
> -- 
> 2.11.0
> 
> 

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