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imx7 IPG_CLK_ROOT and UART's clock

Question asked by Vincent Siles on Jan 2, 2017
Latest reply on Jan 6, 2017 by Vincent Siles

Hi !

I'm wondering about UART clocks:

- from imx7 Reference manual, UART needs two clocks, ipg_clock_root and uart_clock_root

- from linux dts for imx7, we see that both clocks are mapped to IMX7D_UART1_ROOT_CLK

- from linux dts for imx7, we see that "ipg" clock's parent is "ahb", but the clock tree in the reference manual doesn't show this dependency.


Can someone help me clarify the situation:

- do I have to configure IPG_CLK_ROOT to use the UART ?

- why does Linux has both UART's clock set to UART_CLK_ROOT ?

- does IPG_CLK_ROOT depends on AHB_CLK_ROOT (and why ?)

- can IPG_CLK_ROOT be disabled ?