在v821 perf2b开发板上，使用1.2版本sdk，usb口可以正常烧录固件，系统启动后，执行以下命令使能usb host模式：

cat /sys/devices/platform/soc@2002000/soc@2002000:usbc0@0/usb_host

查看dmeg有如下输出：

[   41.731920] sunxi-ehci 44101000.ehci0-controller: 44101000.ehci0-controller supply drvvbus not found, using dummy regulator
[   41.732070] sunxi-ehci 44101000.ehci0-controller: 44101000.ehci0-controller supply hci not found, using dummy regulator
[   41.732260] sunxi-ehci 44101000.ehci0-controller: EHCI Host Controller
[   41.732331] sunxi-ehci 44101000.ehci0-controller: new USB bus registered, assigned bus number 1
[   41.732652] sunxi-ehci 44101000.ehci0-controller: irq 161, io mem 0x44101000
[   41.745804] sunxi-ehci 44101000.ehci0-controller: USB 2.0 started, EHCI 1.00
[   41.746041] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.04
[   41.746053] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[   41.746061] usb usb1: Product: EHCI Host Controller
[   41.746069] usb usb1: Manufacturer: Linux 5.4.220 ehci_hcd
[   41.746078] usb usb1: SerialNumber: sunxi-ehci
[   41.746115] usb usb1: Added to deferred device list
[   41.746143] kobject_add_internal failed for ep_00 (error: -2 parent: usb1)
[   46.850984] random: crng init done

然后在usb口插入usb摄像头，使用lsusb命令看不到任何输出，dmesg里面也没有任何新的信息，已知make kernel_menuconfig中已经使能了UVC驱动：

---->make kernel_menuconfig
---->Device Drivers
---->Multimedia support
---->Media USB Adapters