Re: [PATCH v5 0/2] rust: pci: add capability lookup helpers

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

On Sun Feb 1, 2026 at 7:42 AM GMT, Zijing Zhang wrote:
> It introduces `pci::Device::{find_capability, find_ext_capability}`, thin 
> wrappers around the PCI core helpers (`pci_find_capability()` and 
> `pci_find_ext_capability()`), returning the config-space offset when present.
>
> In `pci::CapabilityId` and  `pci::ExtendedCapabilityId`, Capability IDs are 
> wrapped as newtypes with `from_raw()` plus a set of common constants.
>
> An in-tree user is added to Rust PCI driver sample to exercise the new API.
>
> Previous versions (v4)
> https://lore.kernel.org/rust-for-linux/20260201071450.1614172-1-zijing.zhang@ry.rs/

Also I'd like to mention that Zhi Wang already have a version adding the same
feature on the list, sent before your v1:

https://lore.kernel.org/rust-for-linux/20260126215957.541180-3-zhiw@nvidia.com/

I'd recommend to work together for the feature rather than creating competing
series.

Thanks,
Gary

>
> Testing
> ---
>
> Build
> - x86_64 defconfig-based kernel with Rust enabled (out-of-tree build)
> - `CONFIG_SAMPLES_RUST=y`
> - `CONFIG_SAMPLE_RUST_DRIVER_PCI=y`
>
> Runtime
> - QEMU x86_64 (i440FX) with `-device pci-testdev`
> - QEMU x86_64 (q35) with an NVMe device
>
> Changelog
> ---
>
> v2
> - Run rustfmt on samples/rust/rust_driver_pci.rs to fix rustfmtcheck.
>
> v3
> - Base on pci/next.
> - Add `CapabilityId`/`ExtendedCapabilityId`, switch `find_*capability()`
>   to use them.
> - Document the common ID constants.
> - Update the sample to use typed IDs and exercise the new helpers.
>
> v4
> - Minor doc/style nits.
> - Use early-return style in `find_*capability()`.
>
>
> v5 (current)
> - Fix sample build by using `pdev.as_ref()` for `dev_info!`.
> - Use `as _` in constant definitions.
>
> Zijing Zhang (2):
>   rust: pci: add capability lookup helpers
>   samples: rust: pci: exercise capability lookup
>
>  rust/kernel/pci.rs              | 150 ++++++++++++++++++++++++++++++++
>  samples/rust/rust_driver_pci.rs |  31 +++++++
>  2 files changed, 181 insertions(+)
>
>
> base-commit: ff0e2f679ab0de50a2e9e88fabc1026bc3be04ba