Enable buttons GPIO passthrough

[Linus Walleij]

On Mon, Feb 11, 2019 at 5:54 AM Andrew Jeffery <andrew at aj.id.au> wrote:
> On Fri, 8 Feb 2019, at 22:31, Linus Walleij wrote:

> > > +static int aspeed_gpio_pass_through(struct gpio_chip *chip, unsigned int offset,
> > > +                                   unsigned long usecs)
> > > +{
> > > +       printk("kwin::aspeed_gpio_pass_through is called");
> > > +       return 0;
> > > +}
> >
> > I guess you want to actually implement this too :D
>
> Something to keep in mind is that the ASPEED pinctrl already supports configuring the
> passthrough bits. What we don't want is to cause some inconsistent state between
> the GPIO and pinmux subsystems by just whacking the bits directly.
>
> Looks like we should be able to make it work with PIN_MAP_MUX_GROUP() and using
> some custom name for the state (maybe "passthrough")? It's a half-baked thought
> though so I'm not sure if it's feasible let alone acceptable, but hopefully Linus can
> comment.

Since its a real odd thing this "passthrough" I would certainly prefer if you
could keep it as a custom thing on the pin control side of things. Then I
suppose that you set it up using the device tree and all is fine?

What I'd like to hear from Kwin is a convincing story why Aspeed SoCs
need to do this from userspace, as that seems to be his goal.

Yours,
Linus Walleij