linux-kernel - Re: [PATCH] MIPS: Provide fallback reboot/poweroff/halt implementations

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Message-ID: <alpine.LFD.2.11.1503061059070.15786@eddie.linux-mips.org>
Date:	Fri, 6 Mar 2015 11:08:16 +0000 (GMT)
From:	"Maciej W. Rozycki" <macro@...ux-mips.org>
To:	Andrew Bresticker <abrestic@...omium.org>
cc:	Ralf Baechle <ralf@...ux-mips.org>, linux-mips@...ux-mips.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: Provide fallback reboot/poweroff/halt
 implementations

On Wed, 4 Mar 2015, Andrew Bresticker wrote:

> If a machine-specific hook is not implemented for restart, poweroff,
> or halt, fall back to halting secondary CPUs, disabling interrupts,
> and spinning.  In the case of restart, attempt to restart the system
> via do_kernel_restart() (which will call any registered restart
> handlers) before halting.
> 
> Signed-off-by: Andrew Bresticker <abrestic@...omium.org>
> ---
>  arch/mips/kernel/reset.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/arch/mips/kernel/reset.c b/arch/mips/kernel/reset.c
> index 07fc524..87b1f08 100644
> --- a/arch/mips/kernel/reset.c
> +++ b/arch/mips/kernel/reset.c
> @@ -29,16 +29,36 @@ void machine_restart(char *command)
>  {
>  	if (_machine_restart)
>  		_machine_restart(command);
> +
> +#ifdef CONFIG_SMP
> +	smp_send_stop();
> +#endif
> +	do_kernel_restart(command);
> +	pr_emerg("Reboot failed -- System halted\n");
> +	local_irq_disable();
> +	while (1);

 I think it would make sense to put WAIT or suchlike in the final loop 
so that such a halted system does not suck power unnecessarily.  I think 
bits in arch/mips/kernel/idle.c should do, after some massaging.  As the 
next step perhaps, don't treat it as a NACK for this change.

  Maciej
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