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

Daniel Almeida
2026-02-03T13:38:01Z

> On 3 Feb 2026, at 06:09, 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()?;
>
> 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
>
>

I don’t understand how is this better than the turbofish we currently have.

In other words, how is this:

Clk::get(dev, Some(c_str!("core"))).prepare()?.enable()?;

Better than this:

Clk::<Enabled>::get(/*…*/);

— Daniel