Re: [PATCH 01/11] arch: Export cpu_logical_map to modules

From: Florian Fainelli
Date: Mon Sep 27 2021 - 15:44:05 EST

On 9/27/21 12:32 PM, Rob Herring wrote:
> On Fri, Sep 24, 2021 at 12:06 PM Florian Fainelli <f.fainelli@xxxxxxxxx> wrote:
>> In order to allow drivers/irqchip/irq-bcm7038-l1.c to be built as a
>> module and usable in GKI, export cpu_logical_map or __cpu_logical_map
>> towards the modules.
> This is the usage:
> #ifdef CONFIG_SMP
> cpu = intc->cpus[cpu_logical_map(smp_processor_id())];
> #else
> cpu = intc->cpus[0];
> #endif
> This is totally broken! cpu_logical_map() takes the logical cpu
> number, 0-N, and returns the MPIDR which you then use as an array
> index.

There is no MPIDR on MIPS, which is where this code is being primarily
used as-is. On ARM/ARM64 the driver is used as a second level interrupt
controller with only a single "bank" of registers as opposed to one
per-CPU, meaning that we would always use intc->cpus[0] because you
cannot change the interrupt affinity of a second level interrupt
controller AFAICT. Maybe the above deserves to be made CONFIG_SMP &&
CONFIG_MIPS somehow.