am335x内核启动和插入usb设备 错误PM: Cannot get wkup_m3_ipc handle

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I would not worry about that output unless you are seeing unexpected behavior with the AM335x power management.

I see the same thing when booting my beaglebone black. That error output “PM: Cannot get wkup_m3_ipc handle” gets printed in the am33xx_pm_probe function of the power management driver for AM335x. It prints if the wkup_m3 is not yet available during bootup. If the error occurs, the am33xx_pm driver just waits for a bit to give wkup_m3 more time to initialize, then it tries to run its probe function again.

So the error output does not necessarily mean something is wrong. It just means that the AM335x tried to initialize its power management driver before all of the driver’s required resources were initialized, so it delayed its initialization until later in the boot process.