Hello George Fukutomi,
In previous IMX6 family such as 6SL,6SLX, the ARM_CLK_ROOT has s feedback clock path to CCM. This then can be MUXed to CLKO to be observed on a pad, and ARM_CLK_ROOT is after a static /2 divider, which is exactly the ARM domain divider in the pdf.
In 6UL, the ARM_CLK_ROOT is also after a static /2 divider, but the design does not export ARM_CLK_ROOT to CCM, hence we cannot route ARM_CK_ROOT on CLKO on 6UL (please refer to the definition of CCOSR in RM).
Therefore, the 6UL’s RM should be updated to change the comment in Figure 18-3. Clock Tree: “clock source goes to ARM Domain and returns to CCM” to “clock source goes to ARM Domain”
Please also refer to the thread below:
i.MX6UL: CCM_CLKO2 arm_clk_root on SD1_DATA2 pad
Regards,
