USB - Qualcomm Dragonwing Documentation

The Universal Serial Bus (USB) supports data exchange and power supply between electronic devices at speeds from 1.5 Mbps (low speed) up to 10 Gbps (SuperSpeed Plus). The IQ-8275 uses the Synopsys DesignWare Core SuperSpeed USB 3.x controller connected to USB2 PHY (UTMI) and USB3 PHY (PIPE) interfaces. The board features three USB connectors: two Type-C (USB0, USB1) and one micro-USB (USB2).

Controllers

Controller	Address	Max Speed
USB0	0xa600000	USB 3.x SuperSpeed
USB1	0xa800000	USB 3.x SuperSpeed
USB2	0xa400000	USB 2.0 High Speed

Features

Hardware Features

Feature	Description
Dual-Role Device (DRD)	Host and device modes with dynamic role detection
USB 3.1 Gen1	SuperSpeed 5 Gbps on USB0 and USB1
USB 2.0 High Speed	480 Mbps on all controllers
xHCI	eXtensible Host Controller Interface compliance
Transfer types	Control, bulk, interrupt, isochronous

Software Features

Peripheral mode: Mass Storage, Diagnostics (FunctionFS), RNDIS, NCM Host mode: xHCI, HID/MS/Hub class drivers, UVC (USB camera), Link Power Management

Configuration

Runtime Power Management

echo auto > /sys/bus/platform/devices/a600000.usb/power/control
echo 2000 > /sys/bus/platform/devices/a600000.usb/power/autosuspend_delay_ms
cat /sys/bus/platform/devices/a600000.usb/power/runtime_status

Prevent Suspend During Composition Switch

echo on > /sys/bus/platform/devices/a600000.usb/power/control
# Perform composition switch
echo auto > /sys/bus/platform/devices/a600000.usb/power/control

USB Camera

The IQ-8275 supports USB cameras that comply with the USB Video Class (UVC) standard via the uvcvideo kernel driver, exposing devices as /dev/videoX.

Detect the camera

lsusb
v4l2-ctl --list-devices
ls -l /dev/v4l/by-id/

Check supported formats

yavta /dev/video2 --enum-formats

Stream video

yavta
GStreamer

yavta -f MJPEG -s 1280x720 -t 1/30 -c10 -F/home/ubuntu/test.jpeg /dev/video2

export XDG_RUNTIME_DIR=/run/user/$(id -u ubuntu)
export WAYLAND_DISPLAY=wayland-1

gst-launch-1.0 -e v4l2src device=/dev/video2 ! \
  video/x-raw,format=YUY2,width=1280,height=720,framerate=30/1 ! \
  videoconvert ! waylandsink fullscreen=true

Verification

lsusb                              # List connected USB devices
cat /sys/kernel/debug/usb/devices  # Detailed device info
cat /sys/kernel/debug/usb/a600000.usb/mode        # Check USB mode
cat /sys/kernel/debug/usb/a600000.usb/link_state  # Check link state

Debugging

mount -t debugfs none /sys/kernel/debug
echo 1 > /sys/kernel/debug/tracing/events/dwc3/enable
echo 1 > /sys/kernel/debug/tracing/events/xhci-hcd/enable
cat /sys/kernel/debug/tracing/trace

Troubleshooting

USB Device Not Enumerated

cat /sys/kernel/debug/usb/a600000.usb/mode
cat /sys/kernel/debug/usb/a600000.usb/link_state
dmesg | grep -i usb

Rebind gadget: qusb unbind && qusb bind
Check cable connection and power rails

USB Camera Not Working

lsusb
ls /dev/video*
dmesg | grep -i uvc
lsmod | grep uvcvideo

Composition Switch Fails

echo on > /sys/bus/platform/devices/a600000.usb/power/control
qusb setpid <PID>
echo auto > /sys/bus/platform/devices/a600000.usb/power/control

​Controllers

​Features

​Hardware Features

​Software Features

​Configuration

​Runtime Power Management

​Prevent Suspend During Composition Switch

​USB Camera

​Verification

​Debugging

​Troubleshooting

​Resources