Detect iMX8QM USB overcurrent

fmonte — Wed, 01 Jul 2020 07:45:37 GMT

Hello,
there are two signals, CONN_USB_OTGx_OC, that can be obtained by muxing two pads:

SC_P_USB_SS3_TC2_CONN_USB_OTG1_OC
SC_P_USB_SS3_TC3_CONN_USB_OTG2_OC

Is it possible to get the USB overcurrent status from Linux? How?

The Reference Manual does not talk about those signals. I have tried to dump all USB-related memory mapped registers in both level conditions (CONN_USB_OTGx_OC high and low). However, all the differences are on undocumented registers (eg. 0x5B1000B0).

(In our design those pads are connected to the fault output pin of a DCDC step-down converter).

Thank you
Francesco

Re: Detect iMX8QM USB overcurrent

jamesbone — Mon, 06 Jul 2020 22:14:41 GMT

Hello you can do it by enabling and detecting the overcurrent interrupt and clear the PP bit in the PORTSC1 register.

Please find more information here:

- dtb/pad settings: pads-imx8qm.h\pinctrl\dt-bindings\include - linux-imx - i.MX Linux kernel .

- 8QM RM - pad/mux control for USB_SS3_TCX (starting with section 9.2.5.1.166)

topic Re: Detect iMX8QM USB overcurrent in i.MX Processors

Detect iMX8QM USB overcurrent

Re: Detect iMX8QM USB overcurrent