Why does a u-boot hang and reset happen when the RSU command -> linux_qspi_enable -> RSU command sequence is issued from u-boot-socfpga 2021.04

Due to a problem in the u-boot-socfpga (https://github.com/altera-opensource/u-boot-socfpga) 2021.04 software a u-boot hang followed by a reset may occur after enabling the QSPI. 

This problem may be seen using U-Boot CLI commands:

1.    rsu display_dcmf_version (1st RSU command)
2.    sf probe (this is part of the linux_qspi_enable command, that enables the QSPI node in the Linux DTB, this is part of the flow followed to launch Linux ).
3.    rsu display_dcmf_version (2nd RSU command).
4.    A hang may occurs here,  followed by a  reset if the watchdog is enabled

This probems occurs because the QSPI is being initialized twice, allocating memory for the QSPI device each time, without fully invalidating initial memory region. 
 

This problem is fixed in u-boot-socfpga 2021.04 and later  (https://github.com/altera-opensource/u-boot-socfpga) .   Commit: a0a4a265f7395a938226b08142c4e2234fdead5e.