Re: [PATCH v2 5/5] gpio / ACPI: Add support for ACPI GPIO operation regions

From: Mika Westerberg
Date: Fri Mar 14 2014 - 07:04:57 EST


On Fri, Mar 14, 2014 at 11:53:30AM +0100, Linus Walleij wrote:
> On Thu, Mar 13, 2014 at 4:18 PM, Mika Westerberg
> <mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> > On Thu, Mar 13, 2014 at 03:32:01PM +0100, Linus Walleij wrote:
>
> >> > + case ACPI_IO_RESTRICT_OUTPUT:
> >> > + gpiod_direction_output(desc, pull);
> >>
> >> Can you explain why the fact that the line is pulled down affects the
> >> default output value like this? I don't get it.
> >
> > That's the thing - ACPI doesn't tell us what is the initial value of the
> > pin. There is no such field in GpioIo() resource.
> >
> > So I'm assuming here that if it says that the pin is pulled up, the default
> > value will be high.
>
> OK! So exactly that statement is what I want to see as a comment
> in this switch case.

Sure. I'll add that comment to the next version of this patch.
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