[U-Boot] USB enumeration problem on iMX53 hardware

[Gérald Germain]

Dear all,

I am working on adding support for Host USB on iMX53smd platform. The work is based on iMX53loco code which already support Host USB.
Everything is working as it is supposed to. Different flash usb key are correctly enumerated and detected (and correctly manage by usb_storage module). Even usb to serial converters are correctly enumerated.
But I have a problem with a 3G modem which is not correctly enumerated. In fact the enumeration does not detect anything as if no device was connected. But when linux is booted on the platform, this 3G modem is correctly enumerated by linux kernel.

I added usb debug traces in u-boot. The traces show "Port 4 Status 101 Change 1" response to usb_control_msg call after the call to usb_hub_power_on when the usb flash key is used. When I use the 3G modem device, the response is Port 4 Status 100 Change 0 after the usb_hub_power_on. So it seems that the usb hub do not detect the 3G modem device (the flag USB_PORT_STAT_C_CONNECTION is correctly set in the response when using flash usb key but not set when I use the 3G modem).
Again, the enumeration process for the 3G modem work correctly with the linux kernel, so I could reasonably think that there is not hardware problem on usb hub and 3G modem usb key.

Does one of you has already encountered a similar problem and/or has an idea of what could cause this ?

Gérald