Re: [PATCH 07/12] drm/tyr: Add generic slot manager

[Alice Ryhl <aliceryhl@google.com>]

On Sat, Feb 21, 2026 at 09:44:45AM -0300, Daniel Almeida wrote:
> 
> 
> > On 21 Feb 2026, at 08:17, Alice Ryhl <aliceryhl@google.com> wrote:
> > 
> > On Thu, Feb 12, 2026 at 11:11:13AM +0100, Boris Brezillon wrote:
> >>> +type LockedSeat<T, const MAX_SLOTS: usize> = LockedBy<Seat, SlotManager<T, MAX_SLOTS>>;
> >>> +
> >>> +impl<T: SlotOperations, const MAX_SLOTS: usize> Unpin for SlotManager<T, MAX_SLOTS> {}
> >> 
> >> Do we really need to explicitly flag this type Unpin? I thought this
> >> was the default if the struct is not pinned (and it's not AFAICT).
> > 
> > It may be cleaner to add `#[pin_data]` to the struct and rely on the
> > Unpin impl it generates.
> > 
> > In general, the default Unpin implementation is to inherit from the
> > fields. When you add #[pin_data], it's changed to only inherit from
> > fields marked #[pin]. By adding #[pin_data] but not marking any fields
> > #[pin], it will be Unpin unless any of the zero fields marked #[pin] are
> > Unpin, i.e. it will always be Unpin.
> 
> Why do we need this if all fields are Unpin?

Its fields are not necessarily Unpin. 'manager' could be any type,
including !Unpin types.

Adding #[pin_data] without marking any fields #[pin] is equivalent to
the explicit impl Unpin the patch has now.

> >>> +        // FIXME: Annoying manual copy. The original idea was to not add Copy+Clone to SeatInfo,
> >>> +        // so that only slot.rs can change the seat state, but there might be better solutions
> >>> +        // to prevent that.
> >> 
> >> Okay, I guess we want some inputs from Daniel and/or Alice on that one.
> > 
> > You could consider only implementing Clone. That way, copies do not
> > happen unless you do so explicitly. Or add a private method on the type
> > that has the same function as Clone if you do not wish to expose it.
> 
> Please check my solution where clone is not needed.

If you do not need to return it from the function, then that's fine too,
of course.

Alice