i.MX ProcessorsのトピックImx8mm USB VBUS force enable (manufacturing test)

Imx8mm USB VBUS force enable (manufacturing test)

heisenbug — Tue, 01 Apr 2025 13:37:23 GMT

I am looking for a way to force the VBUS on/(off) even though nothing is connected.

I have tried setting the /sys/class/usb_role/ci_hdrc.0-role-switch/role "host". But this does not in it self trigger the enable.

The USB switching work seemingly perfect in normal usage (Switching automatically depending of a device or a host being connected). This is purely for tests in production.

Also when i have a device connected and forces the "role" of the IMX to be device, it still keeps supplying VBUS.

Maybe you can clear my confusion.

Re: Imx8mm USB VBUS force enable (manufacturing test)

JorgeCas — Wed, 02 Apr 2025 17:48:08 GMT

Hello,

If USB is operating as host, VBUS will be on always.

You could try change MUX options to "force" this behavior. For example:

Turn on USB bus:

devmem2 0x30330058 w 0x00000001

Turn off USB bus:

devmem2 0x30330058 w 0x00000000

Best regards.

Re: Imx8mm USB VBUS force enable (manufacturing test)

heisenbug — Thu, 17 Apr 2025 11:33:44 GMT

Sorry for late reply, when testing this it does not change the VBUS neither in host mode (with device connected) nor without anything connected.

Re: Imx8mm USB VBUS force enable (manufacturing test)

heisenbug — Thu, 17 Apr 2025 11:37:54 GMT

clarifying: I cannot turn if off in host mode:

devmem2 0x30330058 w 0x00000000

nor turn it on, when nothing connected:

devmem2 0x30330058 w 0x00000001

Note: I am using devmem from busybox instead,, but I regards that as not an factor.