[IMPORTANT] Documented that `input_vendor_id`, and `input_product_id` are used by udev

[davidhedlund]

Description

Until this issue has been solved it will be impossible to duplicate files and modify the input_device, to make controllers compatible with linuxraw, or udev for with multiple Linux kernel versions, or BlueTooth/USB:

• [IMPORTANT feature request]: Support multiple input_device, input_device_display_name, input_vendor_id, and input_product_id variables #16907

In RetroArch, the linuxraw and udev drivers rely on input_device instead of input_vendor_id and input_product_id. These drivers automatically select the autoconfig file that matches the name used by the active Linux kernel.

However, when using udev, RetroArch still generates input_vendor_id and input_product_id, even though they aren't necessary. This behavior is not present in linuxraw. The issue with udev creates the impression that users need to comment or uncomment these IDs to choose which udev autoconfig file to use, especially when multiple autoconfig files are available—a common scenario for both non-HID and HID autoconfig files.

Expected behavior

The configuration should be as follows:

input_driver = "udev"
input_device = "Pro Controller"

Also, input_driver and input_device should not be required by PR checks for udev (they are not required by linuxraw)

Actual behavior

udev: The configuration currently includes unnecessary vendor and product IDs:

input_driver = "udev"
input_device = "Pro Controller"
input_vendor_id = "1406"
input_product_id = "8201"

linuxraw

input_driver = "linuxraw"
input_device = "Pro Controller"

Steps to reproduce the bug

• Change the controller profile directory.
• Navigate to Settings -> Drivers -> Controller, and select "udev".
• Restart RetroArch to apply the new setting.
• Go to Settings -> Input -> RetroPad Binds -> Port 1 Controls, and click on "Save Controller Profile".
• Repeat step 1-3 but select "linuxraw" in step 1

Todo list

After resolving the issue, please remove input_driver and input_device from the following autoconfig files that I am maintaining:

• DualSense
• Nintendo Switch Pro Controller
• Nintendo Switch Pro Controller (non-HID)
• DualShock 4 v2

Newly created PRs that can be used to diagnose this issue:

• [Ready for RetroArch 1.20.0] udev: Update Sony Interactive Entertainment DualSense Wireless Controller.cfg retroarch-joypad-autoconfig#1140
• [Ready for RetroArch 1.20.0] udev: Update and rename Nintendo Co., Ltd. Pro Controller.cfg to Nintendo Switch Pro Controller retroarch-joypad-autoconfig#1186

Version/Commit

• RetroArch: 1.19.1