Hi, I'm testing OP-TEE on the IMX6 Sabre SD board and my objective is to setup a UART communication between the TEE and an external device. I successfully enabled the UART and I'm able to establish the serial link, but in order to increase the security level, I would like to manage the CSU, so the UART (UART4 in my case) will only be available for secure world and not for normal world (a Linux Yocto-based config). If I set CSL35[23:16] to 0xFF, everything works. If I set CSL35[23:16] to 0x33, I have a core data-abort error as soon as the TEE tries to write on the UART. The fault seems to be a asynchronous external abort... Does anyone already succeed to enable the CSU on IMX6 ? I don't really understand the role of the HP Register field. Maybe the TZASC (Trust Zone Address Space Config) must be initialized first ? Thanks for your help.