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Booting u-boot using jtag not working

Question asked by Almaz Khamidullin on May 13, 2020
Latest reply on May 27, 2020 by Almaz Khamidullin

Hi!

Have custom pcb based on IMX6ULL.

Current state of BOOT_MODE[1:0] pins is 10b. ECSPI3 selected as boot interface by GPIO boot override pins

After powering it starts to load from SPI flash IC as expected.

OpenOCD on JTAG interface works well. There are no errors on running following commands:

reset init; arm core_state arm; halt

load_image u_boot.imx 0x877ff400

resume 0x87800000

 

Now we are developing mass production script to burn fuse bits.

Step 1 - u-boot image to be loaded via jtag using command above;

Step 2 - fuse bits buring from u-boot command line;

 

But we have lot of errors on jtag interface in a case of BOOT_MODE0 and BOOT_MODE1 both pulled down, e.g. BOOT_MODE[1:0] = 00b:

 

> reset init; arm core_state arm; halt
adapter speed: 2000 kHz
JTAG scan chain interrogation failed: all zeroes
Check JTAG interface, timings, target power, etc.
Trying to use configured scan chain anyway...
imx6ull.dapA7: IR capture error; saw 0x0f not 0x01
Bypassing JTAG setup events due to errors
Reseting ....
imx6ull.cpu.0: ran after reset and before halt ...
target halted in Thumb state due to debug-request, current mode: Supervisor
cpsr: 0x400001f3 pc: 0x00008890
MMU: disabled, D-Cache: disabled, I-Cache: enabled
core state: ARM
Polling target imx6ull.cpu.0 failed, trying to reexamine
imx6ull.cpu.0: hardware has 6 breakpoints, 4 watchpoints

 

> load_image u-boot.imx 0x877ff400
DAP transaction stalled (WAIT) - slowing down
Timeout during WAIT recovery
Failed to write memory at 0x80070080
JTAG-DP STICKY ERROR
JTAG-DP STICKY ERROR
Could not read DSCR register
JTAG-DP STICKY ERROR
Could not read DSCR register
JTAG-DP STICKY ERROR
Polling target imx6ull.cpu.0 failed, trying to reexamine
JTAG-DP STICKY ERROR
Could not initialize the APB-AP
Examination failed, GDB will be halted. Polling again in 100ms
JTAG-DP STICKY ERROR
Polling target imx6ull.cpu.0 failed, trying to reexamine
JTAG-DP STICKY ERROR
Could not initialize the APB-AP
Examination failed, GDB will be halted. Polling again in 300ms
JTAG-DP STICKY ERROR
Polling target imx6ull.cpu.0 failed, trying to reexamine
JTAG-DP STICKY ERROR
Could not initialize the APB-AP
Examination failed, GDB will be halted. Polling again in 700ms
JTAG-DP STICKY ERROR
Polling target imx6ull.cpu.0 failed, trying to reexamine
JTAG-DP STICKY ERROR
Could not initialize the APB-AP
Examination failed, GDB will be halted. Polling again in 1500ms

 

What did I miss? Why does it works when u-boot already booted from SPI IC?

JTAG_MOD pulled up to 3.3V.

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