Problem with GPT example on IMX7

I would like to use the GPT timer on M4 Core of the IMX7. When I start the freertos GPT example from U-boot without booting the Linux System the demo work fine. When I boot the M4 and Linux System the GPT example stop. Where is the Problem?

There is a resource conflict in one of the clock sources used by the example. I suggest to use the 24MHz clock as source for both timers (GPTA and GPTB).

GPTB seems to rely on the System PLL PFD0, which seems to be
influenced by Linux’ SDHC driver. Freezes of both systems have been
observed. Disabling the SDHC driver on the Linux side or using the
24MHz clock source for GPTB seem to avoid freezes.

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