USBIsochronousStreamInEndpoint frame_finished strobe never fires when TRANSFERS_PER_MICROFRAME > 0

[BrettRD]

I'm using the examples/usb/isochronous_count.py but substituting the memory-like USBIsochronousInEndpoint endpoint for a stream-like USBIsochronousStreamInEndpoint.
This is USB2 high speed, with 3 packets per microframe. frame_finished simply never goes off.

Without frame_finished, isochronous endpoints can't be made to synchronise with the USB frame if their transactions are greater than 1k byte.

data_requested is behaving itself, at least the docs say it strobes at the top of a packet.

Digging a bit deeper, I can see the bytes_left_in_packet counter is behaving itself, but bytes_left_in_frame is being reset to its user-specified value at the top of every packet instead of every frame

bytes_left_in_frame is reset during interface.tokenizer.new_frame signal, suggesting the tokenizer is going off on every packet instead of every frame or even microframe.

[BrettRD]

I hooked the tokenizer's frame number into the payload data, and I'm seeing 8x 1k (expected 24x 1k) packets carrying the same frame number in both variants of iso IN endpoint.

This rules out the once-per-packet theory above and suggests the tokenizer new_frame is referring to 8kHz microframes, and that I'm simply not getting the 2 additional transfers per microframe TRANSFERS_PER_MICROFRAME = (2 << 11)

This could easily be a host-side issue with my driver, is there a known-good example for the host-side software to match the isochronous_count.py example?

Should I put my (possibly broken) C libusb driver into a pull request for the examples folder?