linux-kernel - Re: [PATCH v3 7/7] ARM: sun8i: smp: Remove the disabling of CPU0

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Date:   Mon, 19 Feb 2018 09:54:08 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Mylène Josserand <mylene.josserand@...tlin.com>
Cc:     wens@...e.org, linux@...linux.org.uk, robh+dt@...nel.org,
        mark.rutland@....com, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        clabbe.montjoie@...il.com, thomas.petazzoni@...tlin.com,
        quentin.schulz@...tlin.com
Subject: Re: [PATCH v3 7/7] ARM: sun8i: smp: Remove the disabling of CPU0

On Mon, Feb 19, 2018 at 09:18:37AM +0100, Mylène Josserand wrote:
> On sun8i-a63t, hotplug CPU for CPU0 is currently not working.
> Remove the possibility to disable CPU0 only for sun8i-a83t.
> 
> Signed-off-by: Mylène Josserand <mylene.josserand@...tlin.com>
> ---
>  arch/arm/mach-sunxi/mc_smp.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-sunxi/mc_smp.c b/arch/arm/mach-sunxi/mc_smp.c
> index fec592bf68b4..69d5ae5b3d72 100644
> --- a/arch/arm/mach-sunxi/mc_smp.c
> +++ b/arch/arm/mach-sunxi/mc_smp.c
> @@ -661,8 +661,12 @@ static int sunxi_mc_smp_cpu_kill(unsigned int l_cpu)
>  	return !ret;
>  }
>  
> -static bool sunxi_mc_smp_cpu_can_disable(unsigned int __unused)
> +static bool sunxi_mc_smp_cpu_can_disable(unsigned int cpu)
>  {
> +	/* CPU0 hotplug handled only for sun9i */
> +	if (of_machine_is_compatible("allwinner,sun8i-a83t"))
> +		if (cpu == 0)
> +			return false;

This also means that you have a window in your patch sequence where
you can disable the CPU0 on the A83t. This patch should be earlier.

Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com

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