Re: Interrupt storm from pinctrl-amd on Acer AN515-42

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

On Fri, 28 Dec 2018, Linus Walleij wrote:

> On Fri, Dec 28, 2018 at 12:02 AM Leonard Crestez <cdleonard@xxxxxxxxx> wrote:
> 
> > Digging a little deeper it seems the touchpad interrupt is active on
> > boot and since it's configured as "level" and no touchpad driver is
> > available yet there does not seem to be any way to clear it.
> 
> I think these are called "spurious interrupts".
> 
> > I don't know how this should be handled, booting with an active enabled but
> > unclearable interrupt seems like a platform bug to me. There is even an
> > option to set touchpad to "basic" which does some sort of ps2 emulation
> > but the IRQ issue still happens!
> >
> > One workaround is to explicitly disable the interrupt from the handler
> > if no mapping is found; this will keep it disabled until
> > amd_gpio_irq_set_type is called later.
> 
> I don't know how x86 and ACPI systems usually deal with this stuff
> so I'm kind of lost. On the embedded systems that I develop on,
> I would just disable all interrupts on probe() (usually writing 0x0 in
> some interrupt enable register) and then they will get enabled
> once consumers need them.

That's the right thing to do.

> But I have come to understand that maybe ACPI systems are
> not so happy about drivers doing things like that?

Each driver has to invoke a request_irq() variant, which enables the
interrupt line. So there should be no problem when disabling all interrupts
on probe.

Thanks,

	tglx