Hi, [quick reply because I am completely under the water for the next 2 weeks] On Mar 13 2025, 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. Thanks a lot for this work, though I wonder if your goal is not too big, too far from the HID point of view. HID is simple, and there is only a few bindings that you would need to be able to make "simple" HID drivers. My assumption would be to introduce the binding with a functional but small driver (like one that just changes the report descriptor, or does a sime raw event processing). Then we can look at integrating with the DRM interface. Though it's up to you to decide how you want to play ;) > > 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. K, I'll give you my opinion in the patches as the HID co-maintainer. I do have a very little rust experience, but this is my first in kernel, so I hope the more experience rust people here will chime in as well. Cheers, Benjamin > > 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 > > -- > 2.47.2 > >
