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

[Marc Zyngier]

On 2020-03-25 14:31, Jiaxun Yang wrote:
> ä 2020å3æ25æ GMT+08:00 äå10:15:16, Marc Zyngier <maz@xxxxxxxxxx> åå:
> > On 2020-03-25 13:59, Jiaxun Yang wrote:
> >
> > [...]
> >
> > > > > So probably we can use legacy domain when  MIPS IRQ BASE is in the
> > > > > range of legacy IRQ
> > > > > and switch to simple domain when it's not in that range?
> > > >
> > > > No, see below.
> > > >
> > > > > Here in Loongson systems IRQ 0-15 is occupied by I8259 so I did
> > this
> > > > > hack.
> > > >
> > > > Well, if you have to consider which Linux IRQ gets assigned,
> > > > then your platform is definitely not ready for non-legacy
> > > > irqdomains. Just stick to legacy for now until you have removed
> > > > all the code that knows the hwirq mapping.
> > >
> > > Thanks.
> > >
> > > So I have to allocate irq_desc here in driver manually?
> >
> > No, you are probably better off just dropping this patch, as MIPS
> > doesn't seem to be ready for a wholesale switch to virtual interrupts.
>
> It can't work without this patch.
>
> Legacy domain require IRQ number within 0-15
> however it's already occupied by i8259 or "HTPIC" driver.
>
> Previously Loongson even didn't enable IRQ domain so it's not a 
> problem.

Then your platform is breaking some fundamental assumption that the rest
of the MIPS architecture seem to rely on. You could test for the base
IRQ being 0 and create a legacy domain in this case, but that's really
a horrible hack.

I'm pretty worried about having to address this just 4 days away from
the merge window TBH, as this code hasn't been in -next at all.

That's really Thomas' call, but I'm not very enthusiastic.

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