On 2021-08-20 14:15:55 [+0900], Jeaho Hwang wrote:

So we protect irqs inside hw_ep_priming not to make error cases and
also add a timeout inside the hw_ep_set_halt loop for a walkaround.
The timeout patch is submitted to linux-usb.
( https://marc.info/?l=linux-usb&m=162918269024007&w=2 )

We withdrew this patch since we don't know if disabling irq is the
best solution to solve the problem and udc would work fine with
hw_ep_set_halt walkaround even though hw_ep_prime fails.
But we are still trying to find out the cause of this symptom so We'd
so appreciate it if RT or USB experts share some ideas or ways to
report somewhere. Xilinx doesn't provide any support without their
official kernel :(

The UDC driver sometimes drops the lock and acquires it again. On UP it
would not matter but on SMP/RT the other may acquire lock and do
something with the HW. One thing that you could check if there is any HW
access in between which would affect the behaviour.

Thanks for the discussion Sebastian.

Jeaho Hwang.

Sebastian