Hi, Peter Chen writes: > That's very strange, that means the SoC doesn't know VBUS fails down after detaching from the host. > You could measure the VBUS value at the board, then read the VBUS value at register to confirm it. I have put a scope on VBUS. With kernel 4.9 after detaching, it discharges all the way down to about 500 mV, with 4.19 this discharging stops after about 4 seconds at about 2.4V and remains there. > I just tried my board (imx6sx-sdb), it worked OK at at v5.2-rc5. If you have > memtool (the tool to read physical memory), you could read register OTGSC > at that time using below command: It's already part of /sys/kernel/debug/ci_hdrc.0/registers, but reading from its memory address works equally well. > 0x021841A4: 09242F20 Yup, I have 021841a4: 09240f20, which only differs by TOG_1MS. > # cable detach > 0x021841A4: 09341120 021841a4: 09340d20 With BSV reflecting the stopped discharge. > You could poll the /sys/class/udc/ci_hdrc.0/state to know the connection. > > root@imx6qpdlsolox:~# [ 230.074850] configfs-gadget gadget: high-speed config #1: c > > root@imx6qpdlsolox:~# cat /sys/class/udc/ci_hdrc.0/state <=== cable attached > configured > root@imx6qpdlsolox:~# cat /sys/class/udc/ci_hdrc.0/state <=== cable detached > not attached Good to know. The latter turns out as "suspended", though. Thanks and cheers Kai
Attachment:
kernel-4.9-vbus.PNG
Description: kernel-4.9-vbus.PNG
Attachment:
kernel-4.19-vbus.PNG
Description: kernel-4.19-vbus.PNG
