I am attempting to use an IMX6UL as a JTAG interface utilizing OpenOCD's native bitbang support for the IMX's GPIO.
I have successfully connected to the target at lower speeds such as 100KHz. However, to successfully perform flash functions, I need to set the adapter to speed to at least 500KHz, preferably closer to 1500KHz, and have not yet been able to connect to the target at these higher speeds. I have tried a host of GPIO Pad Control Configurations to optimize the signal output but have yet to find one that can properly handle these high speeds.
Therefore, I have the following two questions:
Which pad are you using?
For example: You could check the pad control setting in the RM.
You could try to set the speed and the SRE of the PAD.