RE: [PATCH 3/4] irqchip/sifive-plic: Separate irq_chip for muiltiple PLIC instances

[Anup Patel]

> -----Original Message-----
> From: Marc Zyngier <maz@xxxxxxxxxx>
> Sent: 18 May 2020 13:45
> To: Anup Patel <Anup.Patel@xxxxxxx>
> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>; Paul Walmsley
> <paul.walmsley@xxxxxxxxxx>; Thomas Gleixner <tglx@xxxxxxxxxxxxx>; Jason
> Cooper <jason@xxxxxxxxxxxxxx>; Atish Patra <Atish.Patra@xxxxxxx>; Alistair
> Francis <Alistair.Francis@xxxxxxx>; Anup Patel <anup@xxxxxxxxxxxxxx>; linux-
> riscv@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH 3/4] irqchip/sifive-plic: Separate irq_chip for muiltiple PLIC
> instances
> 
> On 2020-05-16 17:38, Anup Patel wrote:
> >> -----Original Message-----
> >> From: Marc Zyngier <maz@xxxxxxxxxx>
> 
> [...]
> 
> >> I *have* given you a way to implement that in a better way. But
> >> again, I'd rather you *don't* do it for the reason I have outlined
> >> above.
> >
> > I explored kernel/irq/proc.c and we can achieve what this patch does
> > by implementing irq_print_chip() callback of "struct irq_chip" so we
> > certainly don't need separate "struct irq_chip" for each PLIC instance.
> >
> > I will implement irq_print_chip() callback in v2 series.
> 
> You still haven't explained *why* you need to have this change.
> As it stands, I'm not prepared to take it.
> 

This is only for differentiating interrupts of multiple PLIC instance
In /proc/interrupts.

I will drop this patch since (like you mentioned) contents of
/proc/interrupts is considered an ABI and this patch breaks it.

For now, we can infer the PLIC instance for interrupt X based
on contents of /proc/irq/X/node (i.e. interrupt NUMA node id).

Thanks,
Anup