Hubs no longer work

[jfedor2]

I noticed that USB hubs stopped working some time recently (when plugged into a Pico acting as a host).

I have bisected the issue down to these two commits: d735828, 36d5be4.

[rppicomidi]

@jfedor2 At least with commit d17f8ef, a single hub works fine most of the time. With some drivers, usb_midi_host for example, unplug detection can fail almost all of the time. The polling of hub status immediately after a failed IN or OUT transfer on the unplugged device also fails, and the TinyUSB hub driver never tries again. See issue hathach/tinyusb#2971. As this issue does not happen using the native RP2040 hardware, I would say the issue is most likely in this driver.

[rppicomidi]

If I roll back the library version to 0.5.3, hathach/tinyusb#2971 does not happen anymore. I agree with @jfedor2. Something went wrong after release 0.5.3. I tested main (442af43), release 0.6.1, and 0.6.0 and see the same issue. The last commit that correctly handled a disconnect from a hub while there was a pending transfer was 0f747aa. I know this happens all of the time with a USB MIDI host, and I suspect it happens with USB CDC ACM host, too. @sekigon-gonnoc, any advice on where to look? The change from release 0.5.3 to 0.6.0 was pretty major.