1、修改DTS

• dr_mode: tells Dual-Role USB controllers that we want to work on a
  particular mode. Valid arguments are “host”,
  “peripheral” and “otg”. In case this attribute isn’t
  passed via DT, USB DRD controllers should default to
  OTG.

	usb20_otg: usb@ff400000 {compatible = "rockchip,rk3066-usb", "snps,dwc2";reg = <0x0 0xff400000 0x0 0x40000>;interrupts = <GIC_SPI 66 IRQ_TYPE_LEVEL_HIGH>;clocks = <&cru HCLK_OTG>;clock-names = "otg";dr_mode = "otg";g-np-tx-fifo-size = <16>;g-rx-fifo-size = <280>;g-tx-fifo-size = <256 128 128 64 32 16>;g-use-dma;phys = <&u2phy_otg>;phy-names = "usb2-phy";status = "disabled";};

2、用户空间软件控制
找到USB设备，修改otg_mode即可

# pwd
/sys/bus/platform/drivers/rockchip-usb2phy/ff008000.syscon:usb2-phy@100
# ls
driver           modalias         phy              uevent
driver_override  of_node          power
extcon           otg_mode         subsystem
# cat otg_mode 
host
#