Re: [PATCH v3 1/3] rust: clk: use the type-state pattern

Boris Brezillon
2026-02-03T09:47:37Z

On Tue, 3 Feb 2026 10:09:13 +0100
Boris Brezillon <boris.brezillon@collabora.com> wrote:

> Hello Daniel,
>
> On Mon, 2 Feb 2026 17:10:38 +0100
> Boris Brezillon <boris.brezillon@collabora.com> wrote:
>
> > > > -#[pin_data(PinnedDrop)]
> > > > +#[pin_data]
> > > > pub(crate) struct TyrData {
> > > > pub(crate) pdev: ARef<platform::Device>,
> > > >
> > > > @@ -92,13 +92,9 @@ fn probe(
> > > > pdev: &platform::Device<Core>,
> > > > _info: Option<&Self::IdInfo>,
> > > > ) -> impl PinInit<Self, Error> {
> > > > - let core_clk = Clk::get(pdev.as_ref(), Some(c_str!("core")))?;
> > > > - let stacks_clk = OptionalClk::get(pdev.as_ref(), Some(c_str!("stacks")))?;
> > > > - let coregroup_clk = OptionalClk::get(pdev.as_ref(), Some(c_str!("coregroup")))?;
> > > > -
> > > > - core_clk.prepare_enable()?;
> > > > - stacks_clk.prepare_enable()?;
> > > > - coregroup_clk.prepare_enable()?;
> > > > + let core_clk = Clk::<Enabled>::get(pdev.as_ref(), Some(c_str!("core")))?;
> > >
> > > Ah, more turbofish.. I'd really want to avoid them if possible.
> > >
> > > Any disadvantage on just ask the user to chain `.get().prepare_enable()?`? This
> > > way it is also clear that some action is performed.
> >
> > I've just disc
>
> Sorry, I've hit the reply button before I had finished writing my
> answer. So I was about to say that I had started writing something
> similar without knowing this series existed, and I feel like we'd don't
> really need those prepare_enable() shortcuts that exist in C. We might
> has well just go:
>
> Clk::get(dev, Some(c_str!("core"))).prepare()?.enable()?;

If we want this pattern to work, we also need:

impl<State: ClkState> From<Error<State>> for kernel::error::Error {
fn from(e: Error<State>) -> kernel::error::Error {
e.error
}
}

>
> and have the following variant-specofoc functions
>
> - Clk<Unprepared>::get[_optional]() (no get on Prepared and Enabled
> variants)
> - Clk<Unprepared>::prepare()
> - Clk<Prepared>::{enable,unprepare}()
> - Clk<Enabled>::{disable}()
>
> Regards,
>
> Boris
>