Re: [PATCH v3 08/16] irqchip/gic: Configure SGIs as standard interrupts

[Marc Zyngier]

On 2020-09-16 16:46, Jon Hunter wrote:
> On 16/09/2020 16:10, Marc Zyngier wrote:
> > Hi Jon,
> >
> > +Linus, who is facing a similar issue.
> >
> > On 2020-09-16 15:16, Jon Hunter wrote:
> > > Hi Marc,
> > >
> > > On 14/09/2020 14:06, Marek Szyprowski wrote:
> > > > Hi Marc,
> > > >
> > > > On 01.09.2020 16:43, Marc Zyngier wrote:
> > > > > Change the way we deal with GIC SGIs by turning them into proper
> > > > > IRQs, and calling into the arch code to register the interrupt 
> > > > > range
> > > > > instead of a callback.
> > > > >
> > > > > Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx>
> > > > > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> > > > This patch landed in linux next-20200914 as commit ac063232d4b0
> > > > ("irqchip/gic: Configure SGIs as standard interrupts"). Sadly it 
> > > > breaks
> > > > booting of all Samsung Exynos 4210/4412 based boards (dual/quad ARM
> > > > Cortex A9 based). Here are the last lines from the bootlog:
> > >
> > > I am observing the same thing on several Tegra boards (both arm and
> > > arm64). Bisect is pointing to this commit. Reverting this alone does 
> > > not
> > > appear to be enough to fix the issue.
> >
> > Right, I am just massively by the GICv3 spec, and failed to remember
> > that ye olde GIC exposes the source CPU in AIR *and* wants it back, 
> > while
> > newer GICs deal with that transparently.
> >
> > Can you try the patch below and let me know?
>
> Yes will do.
>
> > @@ -365,14 +354,13 @@ static void __exception_irq_entry
> > gic_handle_irq(struct pt_regs *regs)
> >              smp_rmb();
> >
> >              /*
> > -             * Samsung's funky GIC encodes the source CPU in
> > -             * GICC_IAR, leading to the deactivation to fail if
> > -             * not written back as is to GICC_EOI.  Stash the
> > -             * INTID away for gic_eoi_irq() to write back.
> > -             * This only works because we don't nest SGIs...
> > +             * The GIC encodes the source CPU in GICC_IAR,
> > +             * leading to the deactivation to fail if not
> > +             * written back as is to GICC_EOI.  Stash the INTID
> > +             * away for gic_eoi_irq() to write back.  This only
> > +             * works because we don't nest SGIs...
> >               */
> > -            if (is_frankengic())
> > -                set_sgi_intid(irqstat);
> > +            this_cpu_write(sgi_intid, intid);
>
> I assume that it should be irqstat here and not intid?

Indeed. As you can tell, I haven't even tried to compile it, sorry about 
that.

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