Trouble debugging with JTAG when using the WFI instruction

[nathanpalmer]

I know that the JTAG (SJC) controller is prone to drop off when in WFI mode because the clock source is turned off.  I have read that there is a way to keep the JTAG clock active while in WFI mode on the iMX6 but I could not find the way to do it.

I did find the SJC_GPCCR register but I don't know how to use it?

[AnsonHuang · Accepted solution]

Hi, Nathan

     Which kernel are you using, I think you can try disable WAIT mode.

     For L3.10, you can comment out BM_CLPCR_ARM_CLK_DIS_ON_LPM setting in arch/arm/mach-imx/pm-imx6.c->imx6_set_lpm->WAIT_UNCLOCKED;

     For L3.0.35, you can make sure bit5 of CCM_CLPCR is clear, just clear it after kernel boot up, or just pass "enable_wait_mode=off" in kernel command line to disable WAIT mode.

[nathanpalmer]

I am on Baremetal using some functions from the MX6 SDK 1.1.  Thanks for pointing me to the BM_CLPCR_ARM_CLK_DIS_ON_LPM flag, that is just what I was looking for.  I clear the flag when in DEBUG mode and the JTAG keeps on going.  Thanks.

Side question:  Is there a public repo or release schedule for the Freescale Baremetal SDK? 

[AnsonHuang]

Hi, Nathan

     Sorry that I am not aware of this baremetal SDK, I am from linux BSP team, you can post your question again, hope someone else would help you.