P33M

I strongly suspect that qh->qh_list_entry is uninitialised (or dangling) when touched by dwc_otg_hcd_is_bandwidth_allocated().

This is why you don't pass around void * everywhere - the driver incorrectly passes a pointer to ep->hcpriv in to dwc_otg_hcd_is_bandwidth_allocated, not ep->hcpriv (which should point to the queue...

I'm building with the per-task stack protector enabled to see what the FIQ code looks like. From my understanding, the stack canary value will randomly change and if GCC is...

Crashes for me on bcm2709_defconfig and STACKPROTECTOR_PER_TASK=y. It still crashes with maxcpus=1.

Can you try the top of https://github.com/P33M/linux/tree/dwc_otg_fix ? Seems to work for me.

What is the full output of `sudo lsusb -v` What is the output of `dmesg` prior to the error occurring?

For the source of the original error message, there is a not-well-understood behaviour of the dwc2 hardware where it encounters an error condition and the root port enters the disconnected...

https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=273027 There is a limit of a maximum of 1023 bytes of periodic full-speed data per frame on Pi 4's VL805 USB controller. Your two audio devices have a single...

The workaround isn't working because your hub is incorrectly detected as a full-speed hub (not high speed). Have you updated the firmware+kernel? What is the output of `vcgencmd version` after...

Some time ago we raised this issue with Via and this resulted in a firmware (0138a1) that moved the FS periodic bandwidth cap from 792 bytes/frame to 1024 bytes/frame. There...