[Important] The SDL2 controller driver utilizes UDEV rather than SDL2

[davidhedlund]

Describe the issue

When individuals use the "Set All Controls" feature from the AppImage to create autoconfig files with sdl2, they unknowingly generate udev autoconfig files. This can be risky as they might accidentally upload these files to the GitHub repository at https://github.com/libretro/retroarch-joypad-autoconfig/tree/master/sdl2.

Steps to Reproduce the Bug

1. Delete all files in autoconfig/sdl2/.
2. Start RetroArch.
3. Navigate with the mouse since the fallback controller or keyboard will not work (see related bug: SDL2: Fallback controller not working with SDL2, and interupts the keyboard #13).
4. Go to Settings -> Input -> RetroPad Binds -> Port 1 Controls -> Set All Controls.
5. Bind the buttons as needed.
6. Click on "Save Controller Profile".
7. The generated file contains UDEV data, not SDL2 data.
8. Navigate to Main Menu -> Load Core -> Start Remote RetroPad. When you press the button, it will be shown as normal, even though UDEV is being used instead of SDL2. This can be demonstrated by the following steps:
9. Create an SDL2 autoconfig for the same controller using the Flatpak version of RetroArch.
10. Transfer the Flatpak-generated autoconfig file into the autoconfig/sdl2/ directory for the AppImage.
11. Remove the AppImage-generated file located in autoconfig/sdl2/ from step 6.
12. Relaunch the RetroArch AppImage.
13. The controller will be non-functional.

The issue affects all types of controllers, not just the DualSense, which is used as an example. When evaluating this issue, it is important to avoid relying on controller names. Some controllers, such as the Nintendo Switch Pro Controller in Ubuntu MATE 23.4, have identical names in both udev and SDL2 for Bluetooth and USB connections. However, for DualSense controllers, the name varies between linuxraw and SDL2 when connected via Bluetooth or USB. SDL2 does not change the name based on the connection type. Therefore, it is crucial to assess the differences in input variables instead.

Example for Sony DualSense controller

SDL2

The RetroArch packages for Appimage and Flatpak don't generates identical content.

Appimage with SDL2 (issue)

The Appimage appears to generate udev content with the exception that it add input_driver = "sdl2" instead of input_driver = "udev" to the file:

autoconfig/sdl2/Sony Interactive Entertainment DualSense Wireless Controller.cfg

input_driver = "sdl2"
input_device = "Sony Interactive Entertainment DualSense Wireless Controller"
input_vendor_id = "1356"
input_product_id = "3302"
input_b_btn = "0"
input_y_btn = "3"
input_select_btn = "8"
input_start_btn = "9"
input_up_btn = "h0up"
input_down_btn = "h0down"
input_left_btn = "h0left"
input_right_btn = "h0right"
input_a_btn = "1"
input_x_btn = "2"
input_l_btn = "4"
input_r_btn = "5"
input_l2_btn = "6"
input_r2_btn = "7"
input_l3_btn = "11"
input_r3_btn = "12"
input_l_x_plus_axis = "+0"
input_l_x_minus_axis = "-0"
input_l_y_plus_axis = "+1"
input_l_y_minus_axis = "-1"
input_r_x_plus_axis = "+3"
input_r_x_minus_axis = "-3"
input_r_y_plus_axis = "+4"
input_r_y_minus_axis = "-4"

Flatpak with SDL2 (correct)

autoconfig/sdl2/PS5 Controller.cfg

input_driver = "sdl2"
input_device = "PS5 Controller"
input_vendor_id = "1356"
input_product_id = "3302"
input_b_btn = "0"
input_y_btn = "2"
input_select_btn = "4"
input_start_btn = "6"
input_up_btn = "11"
input_down_btn = "12"
input_left_btn = "13"
input_right_btn = "14"
input_a_btn = "1"
input_x_btn = "3"
input_l_btn = "9"
input_r_btn = "10"
input_l2_axis = "+4"
input_r2_axis = "+5"
input_l3_btn = "7"
input_r3_btn = "8"
input_l_x_plus_axis = "+0"
input_l_x_minus_axis = "-0"
input_l_y_plus_axis = "+1"
input_l_y_minus_axis = "-1"
input_r_x_plus_axis = "+2"
input_r_x_minus_axis = "-2"
input_r_y_plus_axis = "+3"
input_r_y_minus_axis = "-3"

UDEV

The RetroArch packages for Appimage and Flatpak both generates identical content.

Appimage with UDEV (correct)

autoconfig/udev/Sony Interactive Entertainment DualSense Wireless Controller.cfg

input_driver = "udev"
input_device = "Sony Interactive Entertainment DualSense Wireless Controller"
input_vendor_id = "1356"
input_product_id = "3302"
input_b_btn = "0"
input_y_btn = "3"
input_select_btn = "8"
input_start_btn = "9"
input_up_btn = "h0up"
input_down_btn = "h0down"
input_left_btn = "h0left"
input_right_btn = "h0right"
input_a_btn = "1"
input_x_btn = "2"
input_l_btn = "4"
input_r_btn = "5"
input_l2_btn = "6"
input_r2_btn = "7"
input_l3_btn = "11"
input_r3_btn = "12"
input_l_x_plus_axis = "+0"
input_l_x_minus_axis = "-0"
input_l_y_plus_axis = "+1"
input_l_y_minus_axis = "-1"
input_r_x_plus_axis = "+3"
input_r_x_minus_axis = "-3"
input_r_y_plus_axis = "+4"
input_r_y_minus_axis = "-4"

Flatpak with UDEV (correct)

#
autoconfig/udev/Sony Interactive Entertainment DualSense Wireless Controller.cfg

input_driver = "udev"
input_device = "Sony Interactive Entertainment DualSense Wireless Controller"
input_vendor_id = "1356"
input_product_id = "3302"
input_b_btn = "0"
input_y_btn = "3"
input_select_btn = "8"
input_start_btn = "9"
input_up_btn = "h0up"
input_down_btn = "h0down"
input_left_btn = "h0left"
input_right_btn = "h0right"
input_a_btn = "1"
input_x_btn = "2"
input_l_btn = "4"
input_r_btn = "5"
input_l2_btn = "6"
input_r2_btn = "7"
input_l3_btn = "11"
input_r3_btn = "12"
input_l_x_plus_axis = "+0"
input_l_x_minus_axis = "-0"
input_l_y_plus_axis = "+1"
input_l_y_minus_axis = "-1"
input_r_x_plus_axis = "+3"
input_r_x_minus_axis = "-3"
input_r_y_plus_axis = "+4"
input_r_y_minus_axis = "-4"

[davidhedlund]

• [CANNOT REPRODUCE] [IMPORTANT] linuxraw: Mapping variables are ineffective libretro/RetroArch#16856