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Re: [PATCH v3] MIPS: Alchemy: fix wait function

To: Manuel Lauss <manuel.lauss@gmail.com>
Subject: Re: [PATCH v3] MIPS: Alchemy: fix wait function
From: "Maciej W. Rozycki" <macro@linux-mips.org>
Date: Mon, 10 Jun 2013 18:17:24 +0100 (BST)
Cc: Linux-MIPS <linux-mips@linux-mips.org>, Ralf Baechle <ralf@linux-mips.org>
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On Sat, 8 Jun 2013, Manuel Lauss wrote:

> diff --git a/arch/mips/kernel/idle.c b/arch/mips/kernel/idle.c
> index 3b09b88..0c655de 100644
> --- a/arch/mips/kernel/idle.c
> +++ b/arch/mips/kernel/idle.c
> @@ -93,26 +93,27 @@ static void rm7k_wait_irqoff(void)
>  }
>  
>  /*
> - * The Au1xxx wait is available only if using 32khz counter or
> - * external timer source, but specifically not CP0 Counter.
> - * alchemy/common/time.c may override cpu_wait!
> + * Au1 'wait' is only useful when the 32kHz counter is used as timer,
> + * since coreclock (and the cp0 counter) stops upon executing it. Only an
> + * interrupt can wake it, so they must be enabled before entering idle modes.
>   */
>  static void au1k_wait(void)
>  {
> +     unsigned long c0status = read_c0_status() | 1;  /* irqs on */
> +
>       __asm__(
>       "       .set    mips3                   \n"
>       "       cache   0x14, 0(%0)             \n"
>       "       cache   0x14, 32(%0)            \n"
>       "       sync                            \n"
> -     "       nop                             \n"
> +     "       mtc0    %1, $12                 \n" /* wr c0status */
>       "       wait                            \n"
>       "       nop                             \n"
>       "       nop                             \n"
>       "       nop                             \n"
>       "       nop                             \n"
>       "       .set    mips0                   \n"
> -     : : "r" (au1k_wait));
> -     local_irq_enable();
> +     : : "r" (au1k_wait), "r" (c0status));
>  }
>  
>  static int __initdata nowait;

 Not exacly what I had in mind, but this looks good to me too. :)

Acked-by: Maciej W. Rozycki <macro@linux-mips.org>

  Maciej

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