[PATCH] utils: irqchip: plic: Using 1 as default priority value

[Anup Patel]

> -----Original Message-----
> From: guoren at kernel.org <guoren at kernel.org>
> Sent: 24 April 2021 08:14
> To: guoren at kernel.org; anup at brainfault.org
> Cc: opensbi at lists.infradead.org; Guo Ren <guoren at linux.alibaba.com>;
> Anup Patel <Anup.Patel at wdc.com>
> Subject: [PATCH] utils: irqchip: plic: Using 1 as default priority value
> 
> From: Guo Ren <guoren at linux.alibaba.com>
> 
> In linux plic drivers:
> static inline void plic_irq_toggle(const struct cpumask *mask,
> 				   struct irq_data *d, int enable)
> {
> 	int cpu;
> 	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
> 
> 	writel(enable, priv->regs + PRIORITY_BASE + d->hwirq *
> PRIORITY_PER_ID);
> 
> It sets PRIORITY in enable/disable irq, but not during init.
> Actually, priority is no use at all and just keep them the same is enough.
> 
> The motivation of my patch: When we want to run 2 different Linux OS in the
> same SMP system, the second Linux cold boot will flush all priority to zero
> and the patch is to solve the problem.

Don't create separate OpenSBI instances for 2 different OSes.

The OpenSBI domain support allows you to create 2 different domains
for each Linux. Please checkout recent YouTube video on OpenSBI domains

Regards,
Anup

> 
> Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
> Cc: Anup Patel <anup.patel at wdc.com>
> ---
>  lib/utils/irqchip/plic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/utils/irqchip/plic.c b/lib/utils/irqchip/plic.c index
> 7665c62..70e89a6 100644
> --- a/lib/utils/irqchip/plic.c
> +++ b/lib/utils/irqchip/plic.c
> @@ -94,7 +94,7 @@ int plic_cold_irqchip_init(struct plic_data *plic)
> 
>  	/* Configure default priorities of all IRQs */
>  	for (i = 1; i <= plic->num_src; i++)
> -		plic_set_priority(plic, i, 0);
> +		plic_set_priority(plic, i, 1);
> 
>  	return 0;
>  }
> --
> 2.7.4