Re: [PATCH v8 06/11] irqchip: mips-cpu: Convert to simple domain

[Thomas Bogendoerfer]

On Wed, Mar 25, 2020 at 11:54:59AM +0800, Jiaxun Yang wrote:
> The old code is using legacy domain to setup irq_domain for CPU interrupts
> which requires irq_desc to be preallocated.
> 
> However, when MIPS_CPU_IRQ_BASE >= 16, irq_desc for CPU IRQs may end up
> unallocated and lead to incorrect behavior.
> 
> Thus we convert the legacy domain to simple domain which can allocate
> irq_desc during initialization.
> 
> Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
> Co-developed-by: Huacai Chen <chenhc@xxxxxxxxxx>
> Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
> Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
>  drivers/irqchip/irq-mips-cpu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/irqchip/irq-mips-cpu.c b/drivers/irqchip/irq-mips-cpu.c
> index 95d4fd8f7a96..c3cf7fa76424 100644
> --- a/drivers/irqchip/irq-mips-cpu.c
> +++ b/drivers/irqchip/irq-mips-cpu.c
> @@ -251,7 +251,7 @@ static void __init __mips_cpu_irq_init(struct device_node *of_node)
>  	clear_c0_status(ST0_IM);
>  	clear_c0_cause(CAUSEF_IP);
>  
> -	irq_domain = irq_domain_add_legacy(of_node, 8, MIPS_CPU_IRQ_BASE, 0,
> +	irq_domain = irq_domain_add_simple(of_node, 8, MIPS_CPU_IRQ_BASE,
>  					   &mips_cpu_intc_irq_domain_ops,
>  					   NULL);

this breaks at least IP30 and guess it will break every platform where
MIPS_CPU_IRQ_BASE == 0. add_legacy will always do irq_domain_associate_many(),
while add_simple doesn't do it, if first_irq == 0.

Marc, what is the reason not doing it all the time ? What's the correct
way here to work with irq_domain_add_simple() in this case ?

Thomas.

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