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Subject: Re: [PATCH RFC] irqchip: gic-v3: Support forced cpu irq affinity
 setting
To: Alim Akhtar <alim.akhtar@samsung.com>, tglx@linutronix.de,
        linux-kernel@vger.kernel.org
References: <CGME20170808091129epcas1p48d0523675178cb841d97e64d5baab75f@epcas1p4.samsung.com>
 <1502183093-30327-1-git-send-email-alim.akhtar@samsung.com>
Cc: jason@lakedaemon.net, linux-arm-kernel@lists.infradead.org,
        shaik.ameer@samsung.com, aswani.reddy@samsung.com,
        abhinav.k@samsung.com, alim.akhtar@gmail.com, arjun.kv@samsung.com
From: Marc Zyngier <marc.zyngier@arm.com>
Organization: ARM Ltd
Message-ID: <7ea6b8d3-762a-d4e9-3b64-609b534c3960@arm.com>
Date: Tue, 8 Aug 2017 10:22:07 +0100
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On 08/08/17 10:04, Alim Akhtar wrote:
> Skip check for online cpu mask when setting irq affinity of per cpu timer
> during early startup of not yet online cpu.
> 
> Signed-off-by: Shaik Ameer Basha <shaik.ameer@samsung.com>
> Signed-off-by: Aswani Reddy <aswani.reddy@samsung.com>
> Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
> ---
>  drivers/irqchip/irq-gic-v3.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> Currently when non boot CPUs comes up and if setting of IRQ affinity gets called
> before cpu online status gets updated, gic_mpidr_to_affinity() returns
> undesirable cpu number. Using __force__ flag ignore cpu_online_mask and setup
> the intended cpu affinity for the irq.
> 
> The same approch is used in gicv2 
> (commit: ffde1de64012c: irqchip: Gic: Support forced affinity setting)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index dbffb7a..c238c64 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -640,11 +640,16 @@ static void gic_smp_init(void)
>  static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
>  			    bool force)
>  {
> -	unsigned int cpu = cpumask_any_and(mask_val, cpu_online_mask);
> +	unsigned int cpu;
>  	void __iomem *reg;
>  	int enabled;
>  	u64 val;
>  
> +	if (!force)
> +		cpu = cpumask_any_and(mask_val, cpu_online_mask);
> +	else
> +		cpu = cpumask_first(mask_val);
> +
>  	if (cpu >= nr_cpu_ids)
>  		return -EINVAL;
>  
> 

See

https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/irqchip-4.13&id=65a30f8b300107266f316d550f060ccc186201a3

	M.
-- 
Jazz is not dead. It just smells funny...