USB 3.0 Development and Testing

Host and Device validation

lsusb -t
dmesg | grep -Ei 'xhci|dwc3|superspeed|gen2'
cat /sys/kernel/debug/usb/devices

A SuperSpeed device should show 5000M in lsusb -t; Gen2/SSP platforms may report a higher rate. If it shows only 480M, the U2 path works but the U3 link did not train.

Type-C / DRD

Complete DRD operation requires a CC/PD controller, orientation mux, USB role switch, VBUS control, and synchronized DWC3 mode. HUSB311 plus PS8743 is only one reference design; other CC logic or mux devices require their matching drivers.

ComboPHY conflict

On some T527 designs, PCIe and USB3 share a ComboPHY. When phy_use_sel selects USB3, PCIe cannot use the PHY simultaneously; when PCIe is selected, disable the USB3 nodes. Confirm the actual sharing in the schematic and SoC specification.

Performance

Record enumeration speed, filesystem, block size, cache behavior, CPU load, and transfer direction when testing a USB drive or SSD. Gadget performance also depends on the selected function and the host PC driver.

Common build and flash workflow

cd <ANDROID_TOP>/longan
./build.sh kernel
./build.sh pack

After flashing, confirm the kernel/DTB build timestamp and version so that new changes are not evaluated on an old image.