Power measurement: At idle, Unipro auto power-down reduces driver overhead to <15 mW. Active bulk transfer at 900 MB/s consumes 1.8 W. Existing UFS drivers (e.g., in Android kernels) are host-side block drivers, not USB gadget drivers. Prior USB-to-storage gadgets for eMMC used MSC or UAS but ignored UFS-specific queuing. Our work is the first open design mapping USB streams to UFS command slots. VII. Conclusion and Future Work We have presented a complete USB device driver for UFS 3.1 storage, exploiting command queuing through UAS protocol and Unipro integration. The driver demonstrates near-linear scaling of IOPS with queue depth up to 32, bridging the gap between mobile UFS performance and USB host accessibility.
| Metric | UAS over UFS 3.1 | MSC over eMMC 5.1 | |----------------------------|------------------|-------------------| | Sequential Read (MB/s) | 981 | 232 | | Sequential Write (MB/s) | 874 | 148 | | Random 4K Read (IOPS) | 58,200 | 12,400 | | Random 4K Write (IOPS) | 44,100 | 9,300 | | Max Queue Depth Supported | 32 | 1 | | Command Latency (µs, QD=1) | 112 | 380 | ufs3 usb driver
—UFS 3.1, USB gadget driver, UAS protocol, MIPI M-PHY, embedded storage, command queuing. I. Introduction Universal Flash Storage (UFS) 3.1 has become the de facto non-volatile memory standard for high-performance embedded systems, offering dual-lane MIPI M-PHY at Gear 4 (11.6 Gbps per lane) and command queuing depth of 32. When such storage is exposed to a USB host—e.g., for file transfer, debugging, or mass storage mode—a conventional USB Mass Storage Class (MSC) driver becomes a bottleneck due to its single command-at-a-time design. Power measurement: At idle, Unipro auto power-down reduces