Re: [PATCH] drm/tyr: suppress unread field warnings

[Alice Ryhl <aliceryhl@google.com>]

On Thu, Jan 22, 2026 at 11:05:59AM -0800, Deborah Brouwer wrote:
> On Thu, Jan 22, 2026 at 08:42:02AM +0000, Alice Ryhl wrote:
> > On Wed, Jan 21, 2026 at 04:37:46PM -0800, Deborah Brouwer wrote:
> > > Currently these warnings, as errors, are preventing Tyr driver
> > > from building:
> > > 
> > > error: field `device` is never read
> > >   --> drivers/gpu/drm/tyr/driver.rs:37:5
> > >    |
> > > 36 | pub(crate) struct TyrDriver {
> > >    |                   --------- field in this struct
> > > 37 |     device: ARef<TyrDevice>,
> > >    |     ^^^^^^
> > >    |
> > >    = note: `-D dead-code` implied by `-D warnings`
> > >    = help: to override `-D warnings` add `#[allow(dead_code)]`
> > > 
> > > error: fields `mali` and `sram` are never read
> > >    --> drivers/gpu/drm/tyr/driver.rs:196:5
> > >     |
> > > 195 | struct Regulators {
> > >     |        ---------- fields in this struct
> > > 196 |     mali: Regulator<regulator::Enabled>,
> > >     |     ^^^^
> > > 197 |     sram: Regulator<regulator::Enabled>,
> > >     |     ^^^^
> > > 
> > > error: aborting due to 2 previous errors
> > > 
> > > Suppress these errors so that the Tyr driver will build.
> > > 
> > > Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
> > 
> > I still don't understand why I couldn't reproduce it myself, but
> > assuming it's not just an 1.80.0 issue, below is my review:
> 
> I think the problem is not actually the rust compiler version, but commit
> "0242623384c7 rust: driver: let probe() return impl PinInit<Self, Error>"
> 
> Tyr probe() used to return a fully initialized Pin<KBox<Self>>, so the
> fields existed in an allocated struct which I suppose counted as
> “reading” the fields. But now Tyr probe() returns just a PinInit
> closure which doesn’t count as reading these fields.

I see.

> > >  drivers/gpu/drm/tyr/driver.rs | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
> > > index 2a45d0288825..04c865cb4397 100644
> > > --- a/drivers/gpu/drm/tyr/driver.rs
> > > +++ b/drivers/gpu/drm/tyr/driver.rs
> > > @@ -34,6 +34,7 @@
> > >  
> > >  #[pin_data(PinnedDrop)]
> > >  pub(crate) struct TyrDriver {
> > > +    #[allow(dead_code)]
> > >      device: ARef<TyrDevice>,
> > 
> > Let's use #[expect(dead_code)] so we remember to remove this when a user
> > is added.
> 
> Using #[expect(dead_code)] also fails with 'unfulfilled lint expectation'.
> So I could keep #[allow(dead_code)] or maybe just use an underscore
> _driver too with a comment to explain the issue. What do you think?

Ok, let's use _driver for now. If you send a v2, I'll apply it right away.

Alice