Hi,
We use a custom board with MCIMX6Q6 and we can successfully deploy u-boot or Yocto OS on it using USB interface.
However, when trying to debug e.g. u-boot with Segger J-Link, it fails to download the code into DDR3. So we simplified the task by just connecting with J-Link at command line. This seems to succeed, but when we try to access to any of peripheral memory or write some value to it, the write operation fails. The following is a log snippet:
J-Link>ih
CPU is halted (PC = 0x000027FA).
J-Link>Regs
PC: (R15) = 000027FA, CPSR = 800001F3 (SVC mode, THUMB FIQ dis. IRQ dis.)
Current:
R0 =00000000, R1 =00000000, R2 =00900000, R3 =00000800
R4 =00000002, R5 =00000000, R6 =00000098, R7 =020D8000
R8 =009024B4, R9 =000B0000, R10=00000000, R11=00000000, R12=00000001
R13=0093FF8C, R14=00000DE9, SPSR=00000000
USR: R8 =009024B4, R9 =000B0000, R10=00000000, R11=00000000, R12=00000001
R13=00000000, R14=00000000
FIQ: R8 =00000000, R9 =00000000, R10=00000000, R11=00000000, R12=00000000
R13=00000000, R14=00000000, SPSR=000215B0
IRQ: R13=00000000, R14=00000000, SPSR=24002050
SVC: R13=0093FF8C, R14=00000DE9, SPSR=B9000878
ABT: R13=00000000, R14=00000000, SPSR=08000475
UND: R13=00000000, R14=00000000, SPSR=20041911
J-Link>mem32 0x020bc000 1 <-- Memory read returns nothing
J-Link>w4 0x020bc000 0x30 <-- Memory write fails
Writing 00000030 -> 020BC000
Failed to write memory
Neither peripheral memory read nor write operation work. Since we can connect with J-Link debugger to to read the CPU registers this problem we related to IMX6 rather than to J-Link itself.
Could someone (from NXP?) suggest whether the IMX6 could be locked somehow so that the peripheral memory read/write is not possible at startup?