Re: [PATCH v2 1/3] dt-bindings: gpio: Add binding documentation for gpio-thunderx

[David Daney]

On 01/09/2017 11:36 AM, Linus Walleij wrote:
> On Sat, Jan 7, 2017 at 12:22 AM, David Daney <ddaney.cavm@xxxxxxxxx> wrote:
>
> > From: David Daney <david.daney@xxxxxxxxxx>
> >
> > Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> (...)
>
> > +Optional Properties:
> > +- compatible: "cavium,thunder-8890-gpio", unused as PCI driver binding is used.
> > +- interrupt-controller: Marks the device node as an interrupt controller.
> > +- #interrupt-cells: Must be present and have value of 2 if
> > +                    "interrupt-controller" is present.
> > +  - First cell is the GPIO pin number relative to the controller.
> > +  - Second cell is triggering flags as defined in interrupts.txt.
>
> AFAICT this device has an optional list of interrupts as well?
> One per pin even?

I'm not sure I understand your question.

The GPIO hardware supports an interrupt on each pin.  The underlying 
interrupt mechanism is via PCI MSI-X, which are fully discoverable by 
the driver, so lack of device tree binding for the these underlying 
MSI-X is fully appropriate.  On the other hand, users of the GPIO 
interrupt pins need this "interrupt-controller" and "#interrupt-cells" 
to be able to properly find and configure the proper interrupts.

I said the "interrupt-controller" property was optional, because some 
systems don't use GPIO interrupts and can function without specifying 
that it is also an interrupt controller.


> Yours,
> Linus Walleij