[WIP] Fix USB audio compatibility issue in BAP broadcast source

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Original prompt

Context

PR zephyrproject-rtos#103738 by @larsgk fixed USB Audio on Windows for the Bluetooth shell test overlay (tests/bluetooth/shell/usb_audio.overlay) by changing UNDEFINED terminal/function types to HEADSET types. The issue is that on Windows, using UNDEFINED device class and terminal types in the devicetree results in the USB Audio device not being selectable as an input/output sound device.

However, the same issue exists in samples/bluetooth/bap_broadcast_source/app.overlay which was not addressed by that PR.

Problem

In samples/bluetooth/bap_broadcast_source/app.overlay, line 45 uses:

terminal-type = <OUTPUT_TERMINAL_UNDEFINED>;

This causes the same Windows USB Audio compatibility issue — the USB Audio device is not selectable as an output sound device on Windows.

Required Change

In samples/bluetooth/bap_broadcast_source/app.overlay, change line 45 from:

terminal-type = <OUTPUT_TERMINAL_UNDEFINED>;

to:

terminal-type = <OUTPUT_TERMINAL_HEADPHONES>;

Use OUTPUT_TERMINAL_HEADPHONES (rather than BIDIRECTIONAL_TERMINAL_HEADSET used in the shell test) because the broadcast source sample is output-only (it only has an output terminal, no bidirectional input/output). The OUTPUT_TERMINAL_HEADPHONES constant is the appropriate output terminal type for this use case.

This is consistent with the fix in PR zephyrproject-rtos#103738 which replaced undefined terminal types with specific device types to ensure Windows compatibility.

Reference

• Review comment: Bluetooth: Shell: Fix BAP USB Audio on windows zephyrproject-rtos/zephyr#103738 (review)
• Original PR: Bluetooth: Shell: Fix BAP USB Audio on windows zephyrproject-rtos/zephyr#103738

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