uvc video

Linux kernel UVC for Quanta Computer, Inc. ACER HD User Facing (0408:4035)

master branch based on linux kernel 6.5, should support up to version 6.7

kernel6.2 tag - based on linux kernel 6.1.7

WARNING: kernel 6.8 is known to modify the uvc driver. Don't apply this patch if on kernel 6.8.

Introduction

There is a known issue with the aforementioned device reporting UVC version 1.5 but implementing UVC 1.0a. A working patch is described in https://patchwork.kernel.org/project/linux-media/patch/20230115205210.20077-1-laurent.pinchart@ideasonboard.com/.

On https://bbs.archlinux.org/viewtopic.php?id=284160 there are instructions on how to download the kernel source code and apply the patch. However after kernel reinstallations or upgrades the patch is reversed. Re-downloading and reapplying the patch each time is time consuming and error- prone, since the upstream repository is rather big (over 2GB).

The repo from which this repository is forked presents a nice alternative that is to separate and modify only the necessary files for the UVC patch. However, applying custom kernel module patches is a security hole and should not be done without proper code audit.

This repository aims to be a nice balance between the two approaches. The code in this repo is the same as in the upstream linux repository. There are only added files for describing the patch and for convenience scripts.

Furthermore, to illustrate how one might persist these changes across kernel upgrades, there is a convenience script for archlinux installations that rely on pacman hooks to rebuild and reapply the patch.

Prerequisites

First and foremost, you are about to apply a kernel patch:

Don't be reckless
Get familiar with what this repo is supposed to do. Read apply.sh and the *.patch file.
Optionally, if on archlinux, read what archlinux-deploy.sh does.
Make sure your kernel is supported.
Audit this repository, using the instructions below.

Dependencies

rsync
git
gcc
kernel-headers
(optional) kernel-modules-hook (for archlinux pacman hook)

The last dependency is necessary to keep the current kernel modules headers and prevent the pacman hook from breaking upon kernel upgrades.

Auditing this repository

Download the linux sourcecode from torvalds/linux, checkout the tag related to your kernel version and run diff --recursive ... passing both this repo folder and drivers/media/usb/uvc inside linux repository folder.

NOTE: You are not supposed to see any changes in the files pertaining to both this and the linux repo. If any other changes are spotted either this repository or your local files might have been compromised and you shouldn't apply the patch. Consider opening an issue.

This is what you are supposed to see when auditing this repository:

$ diff --recursive ~/audit/uvc ~/audit/linux/drivers/media/usb/uvc
Only in /home/USER/audit/uvc: apply.sh
Only in /home/USER/audit/uvc: archlinux-deploy.sh
Only in /home/USER/audit/uvc: .git
Only in /home/USER/audit/uvc: .gitignore
Only in /home/USER/audit/uvc: media-uvcvideo-Force-UVC-version-to-1.0a-for-0408-4035.diff
Only in /home/USER/audit/uvc: README.md

Usage

Clone repo
Run sudo bash apply.sh
Optionally, on archlinux, sudo bash archlinux-deploy.sh

gchamon / uvc