Why do I see my MAC registers empty?

Description

In SoCFPGA U-BOOT, when executing a net related command such as 'PING' or  'TFTP', it calls  Designware's MAC driver to initialize the MAC registers every time. The software also calls mac_reset() twice, in the beginning and end of command respectively, which intend to make MAC controller in a certain status. So the MAC's registers keep in reset value before and after executing the commands.

But in case of developing a new board, customer may want to check the MAC registers after executing a net command for debug purpose.

Resolution

In order to get this feature, customer can comment and cancel the mac_reset() in the dw_eth_halt(), which can avoid the MAC go back to reset status after executing the net command and make the MAC registers available for accessing.