Actually there are two questions:
1. Why the otg directory in linux/drivers/usb was removed from kernel 3.10, I've searched the changelog of linux kernel on kernel.org but find nothing.
2. I'm working on designware's hsotg 2.0 IP, I had usb gadget function working by modifying the s3c-hsotg.c driver which originally written for samsung's sox. Then I have host working using the drivers under drivers/staging/dwc2/. If I want a completely otg support, i.e.SRP, HNP protocol, Is is necessary form me to intergrate the s3c-hsotg's code into dwc2 driver? I've seen from the Kconfig under dwc2 directory said that in the future the two drivers will be merged to form a dual-role-driver, how about this work's progress?