Fix USB enumeration problem on macOS.

[dicristina]

The pico-ice board does not appear as an USB device on macOS with default firmware versions 1.3 and 1.4. The logs indicate that USB enumeration fails:

kernel: (AppleUSBXHCI) AppleUSBXHCIDevice: AppleUSBXHCIDevice::transferEvent: no endpoint 1 for event 0x0000010000003700 1b000000 01018001
kernel: (IOAccessoryManager) IOPortTransportState::setNominalSignalingFrequencies(): [Port-USB-C@1: USB2] Setting nominal signaling frequencies... (nominalSignalingFrequenciesHz: YES, nominalSignalingFrequenciesHz.count: 1)
kernel: (AppleUSBXHCI) AppleUSBXHCIRequest: AppleUSBXHCIRequest::finish: transfer completed with status 0xe00002ed
kernel: (IOUSBHostFamily) IOUSBHostDevice@00100000: IOUSBHostDevice::start_block_invoke: device descriptor fragment is invalid
kernel: (IOUSBHostFamily) IOUSBHostFamily::validateEndpointMaxPacketSize: USB 2.0 5.[5-8].3: endpoint 0x00 invalid wMaxPacketSize 0x0000
kernel: (IOUSBHostFamily) usb-drd0-port-hs@00100000: AppleUSBHostPort::enumerateDeviceComplete_block_invoke: enumeration failed
kernel: (IOUSBHostFamily) usb-drd0-port-hs@00100000: AppleUSBHostPort::terminateDevice: destroying 0x0000/0000/0000 (IOUSBHostDevice): enumeration failure
kernel: (IOUSBHostFamily) IOUSBHostDevice@00100000: IOUSBHostDevice::start_block_invoke: device will not be registered for matching

The tests were done on an M2 MacBook with macOS 14.1.

---

This was introduced with commit 5f37b79. The problem is that the delay in the main loop causes the RP2040 to send a lot of NAK responses and the Mac host gives up on the enumeration. I reproduced the same situation with the dev_hid_composite example by adding a sleep_ms(100) in the main loop. A solution is to ensure that USB enumeration has completed before going into the main loop:

while (!tud_ready())
  tud_task();

while (true) {
  // main loop
}

[josuah]

Such an extensive review! I think this is what we are expected to do for TinyUSB. I will merge it here first, but will consider propagating it further to ice_usb_init().

Thank you for the fix!

[josuah]

Indeed, the expected way is to skip everything until enumeration is there. https://github.com/raspberrypi/pico-examples/blob/master/usb/device/dev_hid_composite/main.c#L108

[josuah]

This got incorporated into the new release, along with other fixes. Thank you for this patch! https://github.com/tinyvision-ai-inc/pico-ice/releases/tag/pico-ice-default-v1.5