Re: [PATCH 1/3] rust: gpio: add GPIO module with common definitions

[Linus Walleij]

Hi Kohei,

thanks for your patch!

On Sun, Sep 6, 2026 at 10:46 AM Kohei Ito <koheiito.dev@xxxxxxxxx> wrote:

> Add the top-level GPIO module with minimal common definitions. This
> module is the basis for future Rust GPIO extensions.

Describe what you want to enable by this patch.

- Enabling in-kernel Rust code to use things from the
  GPIO subsystem? (It looks like so.)

- Writing GPIO drivers in rust? (It seems like not.)

> Signed-off-by: Kohei Ito <koheiito.dev@xxxxxxxxx>
(...)

> +/// Describes the logical GPIO level, i.e. taking the ACTIVE_LOW status into account.
> +#[derive(Clone, Copy, PartialEq, Eq)]
> +pub enum LogicalLineLevel {

Neat!

> +/// Describes the raw GPIO level, i.e. the value of its physical line without regard for its
> +/// ACTIVE_LOW status.
> +#[derive(Clone, Copy, PartialEq, Eq)]
> +pub enum PhysicalLineLevel {

No thanks.

We want to hide the actual physical line level inside the
gpiolib (encapsulation).

We should not expose the physical line level at all
unless there is a consumer in the kernel that absolutely
needs this, and there is none.

Yours,
Linus Walleij