Eric,
[quote user="Eric Lee4"]We used to suspect the pull up resistor of the usb0_id. We removed the pull-up resistor of USB0_ID and it makes no differences. [/quote]
I don't think this issue is because of connecting ID pin to power rail. But doing so could damage the device.
[quote user="Eric Lee4"]Our problem is that "sometimes" when the usb0_id is pull to gnd, but drvvbus is not high. [/quote]
In OTG configuration, DRVVBUS pin is indirectly driven by the 2-sec timer, so please scope USB0_VBUS pin, if it does not pulse any more, we will enable more debug messages.
[quote user="Eric Lee4"]And Bin, can you explain home come when I cat /proc/driver/musb_hdrc.0, the otg is back to normal.[/quote]
Sorry, I don't have a good explanation right now, I never seen this behaviour before. The cat command only trigger the driver to read bunch of registers. I cannot think of any reading will trigger the SESSION.