firmware

t4fwdebugtool flowc 10000

xxd -s 0x80000 -l 512 /sys/kernel/debug/cxgb4/0002\:01\:00.4/flash

WHQL

reinstall

provide IPV6 address of PEER in the test GUI when it asked.
disable all NDIS interfaces and run the test.

Enable flow control under debuuger

NDIS registry key to enable flowcontrol in the presence of Debug enabled:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NDIS\Parameters\[DWORD]AllowFlowControlUnderDebugger.

Set this key to 1 and reboot the machine to enable Tx-Flow control with debugger enabled.