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IMX8MM M4 pwm3 signal disappear when linux boot up

Question asked by coin du on Jun 2, 2020
Latest reply on Jun 5, 2020 by coin du

Hi community:

        I use IMX8MM-EVK board to test M4 driver demo,refer to the document, I download the SDK_2.5.0_EVK-MIMX8MM.tar.gz and compile a demo about pwm



       It generate ipwm.bin use SPDIF_TX pin as pwm3 (J1001 number 47).  the set some env in uboot step.


       setenv fdt_file fsl-imx8mm-evk-m4.dtb 

       setenv m4_image ipwm.bin

       setenv m4_boot_addr 0x7E0000

       setenv m4_run 'fatload mmc ${mmcdev}:${mmcpart} ${m4_boot_addr} ${m4_image};bootaux ${m4_boot_addr}'

      setenv mmcboot "run m4_run;${mmcboot}"



On uboot step type `run m4_run` ,can measure the PWM signal with an oscilloscope .

But if i reset the board, when the kernel boot up ,the PWM signal will disappear,It may be that the kernel initialization CCM affects the M4 clock. 

I want to know is there any way to solve this problem.