Re: [PATCH] gpu: nova-core: use a single try_pin_init!() block in probe()

["Gary Guo" <gary@garyguo.net>]

On Sun Sep 27, 2026 at 3:44 PM BST, Danilo Krummrich wrote:
> Just like in Gpu::new() a single try_pin_init!() block makes the code
> more readable.
>
> Besides that, it prepares the code for a proper PCI device enable guard
> that we will get soon.
>
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>
> ---
>  drivers/gpu/nova-core/driver.rs | 105 ++++++++++++++++----------------
>  1 file changed, 54 insertions(+), 51 deletions(-)
>
> diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
> index bdaed5408a00..623d59dcde6e 100644
> --- a/drivers/gpu/nova-core/driver.rs
> +++ b/drivers/gpu/nova-core/driver.rs
> @@ -100,57 +100,60 @@ fn probe<'bound>(
>          pdev: &'bound pci::Device<Core<'_>>,
>          _info: Option<&'bound Self::IdInfo>,
>      ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
> -        pin_init::pin_init_scope(move || {
> -            dev_dbg!(pdev, "Probe Nova Core GPU driver.\n");
> -
> -            pdev.enable_device_mem()?;
> -            pdev.set_master();
> -
> -            Ok(try_pin_init!(NovaCore {
> -                bar: pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0")?,
> -                bar1: {
> -                    let bar1_idx = bar1_resource_index(pdev)?;
> -                    pdev.iomap_region(bar1_idx, c"nova-core/bar1")?
> -                },
> -                // TODO: Use self-referential pin-init syntax once available.
> -                gpu <- Gpu::new(
> -                    pdev,
> -                    // SAFETY: `bar` is initialized above, pinned, and outlives `gpu`.
> -                    unsafe { &*core::ptr::from_ref(bar) },
> -                    // SAFETY: `bar1` is initialized above, pinned, and outlives `gpu`.
> -                    unsafe { &*core::ptr::from_ref(bar1) },
> -                ).pin_chain(|_gpu| {
> -                    #[cfg(CONFIG_NOVA_CORE_SELFTESTS)]
> -                    _gpu.run_selftests(pdev);
> -                    Ok(())
> -                }),
> -                _reg: {
> -                    // TODO: Use `&gpu` self-referential pin-init syntax once available.
> -                    //
> -                    // SAFETY: `gpu` is initialized before this expression is evaluated
> -                    // (`try_pin_init!()` initializes fields in initializer order), lives at
> -                    // a pinned stable address, and is dropped after `_reg` (struct field
> -                    // drop order).
> -                    let gpu = unsafe {
> -                        Pin::new_unchecked(&*core::ptr::from_ref(gpu.as_ref().get_ref()))
> -                    };
> -
> -                    // SAFETY: `NovaCore` is dropped when the device is unbound;
> -                    // i.e. `mem::forget()` is never called on it.
> -                    unsafe {
> -                        auxiliary::Registration::new_with_lt(
> -                            pdev.as_ref(),
> -                            c"nova-drm",
> -                            // TODO[XARR]: Use XArray or perhaps IDA for proper ID
> -                            // allocation/recycling. For now, use a simple atomic counter that
> -                            // never recycles IDs.
> -                            AUXILIARY_ID_COUNTER.fetch_add(1, Relaxed),
> -                            crate::MODULE_NAME,
> -                            NovaCoreApi { gpu, pdev },
> -                        )?
> -                    }
> -                },
> -            }))
> +        dev_dbg!(pdev, "Probe Nova Core GPU driver.\n");
> +
> +        try_pin_init!(NovaCore {
> +            _: {
> +                pdev.enable_device_mem()?;
> +                pdev.set_master();
> +            },
> +
> +            bar: pdev.iomap_region_sized::<BAR0_SIZE>(0, c"nova-core/bar0")?,
> +
> +            bar1: {
> +                let bar1_idx = bar1_resource_index(pdev)?;
> +                pdev.iomap_region(bar1_idx, c"nova-core/bar1")?
> +            },
> +
> +            // TODO: Use self-referential pin-init syntax once available.
> +            gpu <- Gpu::new(
> +                pdev,
> +                // SAFETY: `bar` is initialized above, pinned, and outlives `gpu`.
> +                unsafe { &*core::ptr::from_ref(bar) },
> +                // SAFETY: `bar1` is initialized above, pinned, and outlives `gpu`.
> +                unsafe { &*core::ptr::from_ref(bar1) },
> +            ).pin_chain(|_gpu| {
> +                #[cfg(CONFIG_NOVA_CORE_SELFTESTS)]
> +                _gpu.run_selftests(pdev);
> +                Ok(())
> +            }),

I think this doesn't need to use `pin_chain`? You can do

    gpu <- ...,

    _: {
        #[cfg(...)]
        gpu.run_self_tests(pdev);
    }

I know this is pre-existing but given that you're tidying it up this might do as
well.

Best,
Gary

> +
> +            _reg: {
> +                // TODO: Use `&gpu` self-referential pin-init syntax once available.
> +                //
> +                // SAFETY: `gpu` is initialized before this expression is evaluated
> +                // (`try_pin_init!()` initializes fields in initializer order), lives at
> +                // a pinned stable address, and is dropped after `_reg` (struct field
> +                // drop order).
> +                let gpu = unsafe {
> +                    Pin::new_unchecked(&*core::ptr::from_ref(gpu.as_ref().get_ref()))
> +                };
> +
> +                // SAFETY: `NovaCore` is dropped when the device is unbound;
> +                // i.e. `mem::forget()` is never called on it.
> +                unsafe {
> +                    auxiliary::Registration::new_with_lt(
> +                        pdev.as_ref(),
> +                        c"nova-drm",
> +                        // TODO[XARR]: Use XArray or perhaps IDA for proper ID
> +                        // allocation/recycling. For now, use a simple atomic counter that
> +                        // never recycles IDs.
> +                        AUXILIARY_ID_COUNTER.fetch_add(1, Relaxed),
> +                        crate::MODULE_NAME,
> +                        NovaCoreApi { gpu, pdev },
> +                    )?
> +                }
> +            },
>          })
>      }
>  }
>
> base-commit: 10a6623a24a85708650efad7be15182289403cd7