Re: [PATCH] IIO: Adds ACPI support for ST gyroscopes

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Wed, Mar 25, 2015 at 09:44:34AM +0100, Linus Walleij wrote:
> On Tue, Mar 24, 2015 at 4:06 PM, Mika Westerberg
> <mika.westerberg@linux.intel.com> wrote:
> 
> > This has few problems that I have not yet figured out. Maybe someone
> > here can suggest what to do:
> >
> >  1) Who is responsible in releasing the GPIO?
> >  2) What if the driver wants to use that pin as a GPIO instead? The GPIO
> >     is already requested by the I2C core.
> 
> In the DT usecase we actually specify that in the DTS file
> so we don't have the problem. Either the consumer accesses
> the irqchip API with:
> 
> interrupts = <nn nn>;
> 
> or it accesses the GPIO API with:
> 
> gpios = <nn nn>;

OK, I see.

> so in that sense it is clear what is requested. Then the core
> of course uses gpiochip_lock/unlock_as_irq() to handle the
> case where bugs make a collision (like if both were specified
> and both APIs tries to access the same resource).

Where in the core code gpiochip_lock/unlock_as_irq() is called for
these? At least of_irq_get() doesn't seem to be doing that. Maybe I'm
looking at the wrong place.

> But as long as the DTS file is consistent there is no problem.
> 
> So it seems the ACPI tables are lacking this semantic
> information?

I think the GpioIo/GpioInt separation serves the same purpose. Of course
both refer to GPIO controller instead of interrupt controller.