This is a research project to understand of init_DRAM() function for Allwinner T113-S4 chip on PBkit101-A SOM.

The project is the reduced original project named "spl-pub" in SDK for Allwinner chips from development board manufacturer. There is no public link to their SDK.

Build instruction: make CROSS_COMPILE="your cross-compiler" b=t113_s4 m=fes ddr=ddr3 fes

Result in: fes/fes1.bin; it is the firmware for run from SRAM of T113-S4.

Expected behaviour if run this program using xfel tool: make DDR3 SDRAM initialization, log some info to UART3 and silently exit.

• sudo ./xfel write 0x00028000 fes1.bin
• sudo ./xfel exec 0x000283c8 # see start address for "_start" symbol in linker map file fes/fes1.map

After running this commands, it it possible to use sunxi-fel or xfel tools to do the usual work; but I don't test sunxi-fel.

I change debug log to UART3 (it is "DBUG1" UART connector in PB101-A-BASE development board). Also I change initialization data of DDR3 SDRAM in fes/main/fes1_head.c file.

This works, in contrast of sudo ./xfel ddr t113-s4 command and sunxi-fel tool.

If you want to run without sudo, you need to setup udev rule. See here.

$ sudo echo SUBSYSTEM==\"usb\", ATTR{idVendor}==\"1f3a\", MODE=\"0666\", GROUP=\"plugdev\" >/etc/udev/rules.d/51-t113s4.rules
$ sudo udevadm trigger