linux-kernel - Re: [PATCH RESEND 1/2] arm: berlin: use non-self-cleared reset register to reset cpu

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Date:	Sun, 20 Sep 2015 20:04:01 +0200
From:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To:	Jisheng Zhang <jszhang@...vell.com>, linux@....linux.org.uk
CC:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND 1/2] arm: berlin: use non-self-cleared reset register
 to reset cpu

On 14.09.2015 08:47, Jisheng Zhang wrote:
> In Berlin SoCs, there are two kinds of cpu reset control registers: the
> first one's corresponding bits will be self-cleared after some cycles,
> while the second one's bits won't. Previously the first kind of reset
> control register is used, this patch uses the second kind one to prepare
> for the next hotplug commit.
>
> Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
> ---
>   arch/arm/mach-berlin/platsmp.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-berlin/platsmp.c b/arch/arm/mach-berlin/platsmp.c
> index 34a3753..bde327b 100644
> --- a/arch/arm/mach-berlin/platsmp.c
> +++ b/arch/arm/mach-berlin/platsmp.c
> @@ -17,7 +17,7 @@
>   #include <asm/smp_plat.h>
>   #include <asm/smp_scu.h>
>
> -#define CPU_RESET		0x00
> +#define CPU_RESET		0x20

Jisheng,

I am fine with the patch itself, except that I'd like to rather
rename the 0x00-register to CPU_RESET_SC with a comment about
the self-clearing nature. The 0x20-register would then be named
CPU_RESET_NON_SC and used the way you propose.

Are you fine with me naming the registers accordingly while
applying the patches?

Sebastian

>   #define RESET_VECT		0x00
>   #define SW_RESET_ADDR		0x94
> @@ -31,6 +31,8 @@ static inline void berlin_perform_reset_cpu(unsigned int cpu)
>   	u32 val;
>
>   	val = readl(cpu_ctrl + CPU_RESET);
> +	val &= ~BIT(cpu_logical_map(cpu));
> +	writel(val, cpu_ctrl + CPU_RESET);
>   	val |= BIT(cpu_logical_map(cpu));
>   	writel(val, cpu_ctrl + CPU_RESET);
>   }
>

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