Re: [PATCH RFC 0/3] Initial work for Rust abstraction for HID device driver development

[Benno Lossin]

On Thu Mar 13, 2025 at 5:02 PM CET, Rahul Rameshbabu wrote:
> Hello,
>
> I am a hobbyist developer who has been working on a project to create a new Rust
> HID device driver and the needed core abstractions for writing more HID device
> drivers in Rust. My goal is to support the USB Monitor Control Class needed for
> functionality such as backlight control for monitors like the Apple Studio
> Display and Apple Pro Display XDR. A new backlight API will be required to
> support multiple backlight instances and will be mapped per DRM connector. The
> current backlight API is designed around the assumption of only a single
> internal panel being present. I am currently working on making this new API for
> DRM in parallel to my work on the HID side of the stack for supporting these
> displays.
>
>   https://binary-eater.github.io/tags/usb-monitor-control/
>
> Julius Zint had attempted to do so a year ago with a C HID driver but was gated
> by the lack of an appropriate backlight API for external displays. I asked him
> for permission to do the work need in Rust and plan to accredit him for the HID
> report handling for backlight in the USB Monitor Control Class standard.
>
>   https://lore.kernel.org/lkml/f95da7ff-06dd-2c0e-d563-7e5ad61c3bcc@xxxxxxxxxx/
>
> I was hoping to get initial feedback on this work to make sure I am on the right
> path for making a Rust HID abstraction that would be acceptable upstream. The
> patches compile with WERROR being disabled. This is necessary since Rust treats
> missing documentation comments as warnings (which is a good thing). I also need
> to go in and add more SAFETY comments.
>
> Thanks,
> Rahul Rameshbabu
>
> Rahul Rameshbabu (3):
>   rust: core abstractions for HID drivers
>   rust: hid: USB Monitor Control Class driver
>   rust: hid: demo the core abstractions for probe and remove
>
>  drivers/hid/Kconfig                |  16 ++
>  drivers/hid/Makefile               |   1 +
>  drivers/hid/hid_monitor_control.rs |  42 +++++
>  rust/bindings/bindings_helper.h    |   1 +
>  rust/kernel/hid.rs                 | 245 +++++++++++++++++++++++++++++
>  rust/kernel/lib.rs                 |   2 +
>  6 files changed, 307 insertions(+)
>  create mode 100644 drivers/hid/hid_monitor_control.rs
>  create mode 100644 rust/kernel/hid.rs

I have taken a very quick look and haven't seen any big problems,
there are some minor things, but not worth mentioning for an RFC.

---
Cheers,
Benno