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-9075 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	HS PHY Rails	SS PHY Rails
USB0	0xa600000	USB 3.x SuperSpeed	L7A (0.88V), L6C (1.8V), L9A (3.3V)	L1C, L7A
USB1	0xa800000	USB 3.x SuperSpeed	L7A (0.88V), L6C (1.8V), L9A (3.3V)	L1C, L7A
USB2	0xa400000	USB 2.0 High Speed	VDD_A_USBHS_2_1P8, VDD_A_USBHS_2_3P1	—

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
Link Power Management	ASPM-style LPM for power savings

Software Features

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

Architecture

Layer	Key Components
User Space	`diag-router`, `qusb` — service management, composition switching
VFS	`/dev/ffs-*`, `/sys/kernel/config` — dynamic config, endpoint access
Kernel	`dwc3-qcom`, xHCI, Gadget Framework — dual-role, power management
Hardware	DWC3 Controllers, Femto/QMP PHYs

Configuration

Runtime Power Management

# Enable autosuspend
echo auto > /sys/bus/platform/devices/a600000.usb/power/control
echo 2000 > /sys/bus/platform/devices/a600000.usb/power/autosuspend_delay_ms

# Check status
cat /sys/bus/platform/devices/a600000.usb/power/runtime_status

Runtime PM is not supported for Type-C ports on IQ-9075.

Enable Remote Wake-up (Host Mode)

# Enable wake-up for xHCI
echo enabled > /sys/bus/platform/devices/xhci-hcd.X.auto/power/wakeup

# Enable wake-up for root hubs
echo enabled > /sys/bus/usb/devices/usb1/power/wakeup
echo enabled > /sys/bus/usb/devices/usb2/power/wakeup

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-9075 supports USB cameras that comply with the USB Video Class (UVC) standard via the uvcvideo kernel driver, exposing devices as /dev/videoX.

Detect and Configure

Detect the camera

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

Check supported formats

yavta /dev/video2 --enum-formats

Capture or stream video

yavta
ffplay
GStreamer

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

# YUYV capture
yavta -f YUYV -s 1280x720 -t 1/5 -c10 -F/tmp/test.yuv /dev/video2

ffplay -f v4l2 -framerate 30 -input_format mjpeg -video_size 1920x1080 -i /dev/video2
ffplay -f v4l2 -framerate 30 -input_format yuyv422 -video_size 1920x1080 -i /dev/video2

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

# 720p stream (YUYV = YUY2 in GStreamer)
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

For multi-stream inference with USB cameras, see the Qualcomm IM SDK and the gst-usb-single-camera-app.

Verification

Host Mode

lsusb                              # List connected USB devices
cat /sys/kernel/debug/usb/devices  # Detailed device info
ls /sys/bus/usb/devices/           # USB device tree

Device Mode

cat /sys/kernel/debug/usb/a600000.usb/mode        # Check USB mode
cat /sys/kernel/debug/usb/a600000.usb/link_state  # Check link state
qusb showpid                                       # List compositions

Debugging

Enable USB Tracing

mount -t debugfs none /sys/kernel/debug

# Enable traces
echo 1 > /sys/kernel/debug/tracing/events/dwc3/enable
echo 1 > /sys/kernel/debug/tracing/events/xhci-hcd/enable
echo 1 > /sys/kernel/debug/tracing/events/gadget/enable

cat /sys/kernel/debug/tracing/trace

Collect Register Dumps

mkdir -p /tmp/usb_debug
cat /sys/kernel/debug/usb/a600000.usb/regdump    > /tmp/usb_debug/regdump.txt
cat /sys/kernel/debug/usb/a600000.usb/lsp_dump   > /tmp/usb_debug/lsp_dump.txt
cat /sys/kernel/debug/usb/a600000.usb/mode       > /tmp/usb_debug/mode.txt
cat /sys/kernel/debug/usb/a600000.usb/link_state > /tmp/usb_debug/link_state.txt
dmesg > /tmp/usb_debug/dmesg.txt
lsusb -v > /tmp/usb_debug/lsusb.txt

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
Change composition: qusb setpid <PID>
Check cable connection and power rails

USB Camera Not Working

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

Ensure uvcvideo driver is loaded
Try a different USB port
Verify camera is UVC-compliant

Low Power Mode Not Working

cat /sys/bus/platform/devices/a600000.usb/power/runtime_status
cat /sys/bus/platform/devices/a600000.usb/power/control

Enable autosuspend:

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

Composition Switch Fails

Prevent suspend during the switch:

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

​Architecture

​Configuration

​Runtime Power Management

​Enable Remote Wake-up (Host Mode)

​Prevent Suspend During Composition Switch

​USB Camera

​Detect and Configure

​Verification

​Host Mode

​Device Mode

​Debugging

​Enable USB Tracing

​Collect Register Dumps

​Troubleshooting

​Resources

Controllers

Features

Hardware Features

Software Features

Architecture

Configuration

Runtime Power Management

Enable Remote Wake-up (Host Mode)

Prevent Suspend During Composition Switch

USB Camera

Detect and Configure

Verification

Host Mode

Device Mode

Debugging

Enable USB Tracing

Collect Register Dumps

Troubleshooting

Resources