I am working on adding USB mass storage functionality to embedded device and I need to determine if device is connected to USB host or power-only source (like powerbank). When connected to host, device must stop using mass storage partition (LUN) and unmount it. When disconnected, device must mount it back and start using. This implies only if connected to USB host. When connected to powerbank, device must continue using mass storage. To determine if USB host is connected, I am tracking USB gadget state via `sysfs` in user space. USB gadget state is exposed to `sysfs` only if gadget is bind to UDC and at least one function is enabled. So I am creating gadget with serial and ethernet functions enabled at device startup. When host is detected (state `configured`), I would like to enable mass storage functionality using configfs and disable it when host is disconnected without the need to unbind and bind UDC again. This is not possible with kernel 4.11. The question is why this is not possible and what are the side effects of implementing this? Ros
