Re: [PATCH v3 1/1] pinctrl: add Intel BayTrail GPIO/pinctrl support

[Timur Tabi]

On 04/15/2014 05:01 AM, Mathias Nyman wrote:
> > This device will only be used on an ACPI system, right?  And isn't ACPI
> > supposed to hide all the pinctrl programming from the OS?  I thought
> > that was the whole point behind ACPI and the reason why ARM64 isn't
> > going to use device trees.
>
> This was my starting point as well, and the driver was initially
> submitted as a GPIO driver. But Linus W. suggested pinctrl instead, and
> as he's the maintainer of both those subsystem I trust his judgment.

Do you think, for an ACPI pinctrl driver, that we will need to specify 
any function groups?  When I look at the ASL that configures GPIOs, I 
see only lines like this:

GpioIo (Exclusive, PullDefault, , , , "\\GIO0") {0x1D, 0x1E}

This tells me that ACPI will never use any of the names that are 
defined.  I see that .get_function_name is called on my ACPI system, but 
I don't see where it is used.

The reason I ask is because I would like to make a "generic" ACPI 
pinctrl/gpio driver that doesn't specify any pin groups.  So if we use 
the same pinctrl/gpio hardware on multiple SOCs, the only thing that the 
driver needs from ACPI is the number of pins.

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