Re: [RFC PATCH 0/4] rust: usb: add usb request block abstractions and a user

[Daniel Almeida <daniel.almeida@collabora.com>]

Hi Colin!

> On 12 Jul 2026, at 18:07, Colin Braun <colinbrauncl@gmail.com> wrote:
> 
> This series introduces initial abstractions to allow for the
> implementation of USB drivers in Rust.
> 
> This is an RFC to demonstrate a rough idea on how the USB abstractions
> needed to create drivers in Rust could be implemented.
> 
> The series is broken up into 4 parts:
> 
> 1. USB chapter 9 standard descriptors and constants - Exposes the
>   necessary structs and constants from include/uapi/linux/usb/ch9.h as
>   a new ch9 submodule.
> 
> 2. Interface and endpoint abstractions - Wraps the relevant C structs
>   and functions defined in include/linux/usb.h, allowing drivers to
>   safely query and configure interfaces and their endpoints.
> 
> 3. USB Request Block (URB) abstractions - Creates a safe wrapper around
>   the C `struct urb` to allow Rust drivers to communicate with devices.
> 
> 4. An initial user of the new abstractions - A driver for the GV-USB2
>   composite-usb video capture device.
> 
> Patch 3 is the bulk and core of this series. By their asynchronous
> nature, creating a safe URB abstraction for drivers to use is tricky.
> The goals of the URB abstraction are:
> 
> 1. No `unsafe` needed in driver code. This means providing a way for a
>   driver to safely access private data sent with the URB.
> 2. Drivers are forced to handle the URB status in their completion
>   callback before accessing the URB data.
> 3. Dropping an URB ensures it is not in-flight and frees its resources.
> 4. The URB can be safely resubmitted from the completion callback.
> 
> The patch elaborates on how these goals are achieved in more detail.
> 
> Although the URB abstractions do not include immediate support for bulk
> or interrupt URBs, I believe it creates a foundation conducive to
> future, safe abstractions for them.
> 
> Patch 4 is first user of these USB abstractions. The initial
> implementation is very much bare-bones, only exposing audio data via
> debugfs. It is based on the in-tree STK1160 driver and an old,
> out-of-tree driver written by Isaac Lozano [1].
> 
> [1] https://github.com/Isaac-Lozano/GV-USB2-Driver
> 
> Signed-off-by: Colin Braun <colin.braun.cl@gmail.com>
> ---
> Colin Braun (4):
>      rust: usb: add USB ch9 standard descriptors and constants
>      rust: usb: add usb host interface and endpoint abstractions
>      rust: usb: add urb abstraction with control and isochronous support
>      media: add gv-usb2 audio capture driver

Have you talked to the media people about adding a Rust driver?

> 
> drivers/media/usb/Kconfig            |   1 +
> drivers/media/usb/Makefile           |   1 +
> drivers/media/usb/gv-usb2/Kconfig    |   9 +
> drivers/media/usb/gv-usb2/Makefile   |   1 +
> drivers/media/usb/gv-usb2/driver.rs  | 361 ++++++++++++++
> drivers/media/usb/gv-usb2/gv_usb2.rs |  16 +
> drivers/media/usb/gv-usb2/regs.rs    |  25 +
> include/linux/usb.h                  |   4 +
> rust/kernel/usb.rs                   | 905 ++++++++++++++++++++++++++++++++++-
> rust/kernel/usb/ch9.rs               | 295 ++++++++++++
> 10 files changed, 1613 insertions(+), 5 deletions(-)
> ---
> base-commit: 30e873dd61b044092dbc657c7c67a5d19adfd933
> change-id: 20260712-urb-abstraction-v1-020a67f16cff
> 
> Best regards,
> --  
> Colin Braun <colin.braun.cl@gmail.com>
> 
>