Overview

This PR fixes issue #3311 by adding a bool is_isr parameter to both the low-level DCD functions (dcd_edpt_xfer() and dcd_edpt_xfer_fifo()) and the high-level wrapper functions (usbd_edpt_xfer() and usbd_edpt_xfer_fifo()). This allows both DCD drivers and class drivers to properly handle synchronization based on whether they are being called from ISR context or task context.

Problem

Previously, these functions hardcoded usbd_spin_lock(false) and usbd_spin_unlock(false), assuming they were always called from non-ISR (task) context. However, in some scenarios, these functions may need to be called from ISR context, which requires different locking behavior to avoid deadlocks or race conditions.

Solution

Added a bool is_isr parameter to both the DCD-level and USBD-level functions that indicates the calling context:

• is_isr = false: Called from task context (normal application code, deferred processing)
• is_isr = true: Called from ISR context (interrupt handlers)

This parameter is then passed through the call chain to usbd_spin_lock() and usbd_spin_unlock() to ensure proper synchronization.

Changes

API Updates

• src/device/dcd.h: Updated DCD function declarations to include bool is_isr parameter
• src/device/usbd_pvt.h: Updated USBD wrapper function declarations to include bool is_isr parameter
• src/device/usbd.c: Updated implementations to accept and pass through the is_isr parameter

DCD Driver Updates

Updated all ~30 DCD driver implementations across multiple MCU families:

• STM32, NXP, Nordic, Microchip, Renesas, TI, WCH, Raspberry Pi, Dialog, Nuvoton, Bridgetek, Sony, Mentor Graphics, ValentyUSB, and others
• Modified usbd_spin_lock()/usbd_spin_unlock() calls to use the is_isr parameter
• Added (void) is_isr; to suppress unused parameter warnings where appropriate

Class Driver Updates

Updated all class drivers to pass the appropriate is_isr value:

• Most callers pass false (task context)
• ISR functions like audiod_rx_xfer_isr() and audiod_tx_xfer_isr() pass true (ISR context)
• Updated files: audio, CDC, HID, MSC, MTP, MIDI, USBTMC, NCM, ECM/RNDIS, video, BTH device classes

Test Updates

• Updated unit test mocks to expect the new parameter
• All 21 unit tests pass

Validation

• ✅ All unit tests pass (21/21)
• ✅ STM32F4 CDC_MSC example builds successfully
• ✅ No compilation errors across tested platforms

Example Usage

// DCD level - called from task context (e.g., in usbd.c)
dcd_edpt_xfer(rhport, ep_addr, buffer, total_bytes, false);
// DCD level - called from ISR context (future use)
dcd_edpt_xfer(rhport, ep_addr, buffer, total_bytes, true);
// USBD level - called from task context (most class drivers)
usbd_edpt_xfer(rhport, ep_addr, buffer, total_bytes, false);
// USBD level - called from ISR context (e.g., in audiod_rx_xfer_isr)
usbd_edpt_xfer(rhport, ep_addr, buffer, total_bytes, true);

Fixes #3311

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