Does any integrated USB hub support per-port power control? I'd like to control a directly-attached USB external hard drive to my Linux box.
There is IOCTL_USB_HUB_CYCLE_PORT in Windows that power cycles a port (https://docs.microsoft.com/en-us/windows-hardware/drivers/dd...). My research seems to indicate it doesn't always work. The corresponding utility on Linux has problems on modern hardware but the driver may not be complete.
For both operating systems, you can likely use the autosuspend features, but this is gated by the driver (at least on Linux) and may not be able to reset a malfunctioning device.
For some reason PCIe and USB lack a way to do a hard reset.
[1] https://rwmj.wordpress.com/2015/10/09/usb-per-port-power-swi...
This has worked fairly well, though it exposes some other interesting problems which I suspect are deeper issues in the Linux kernel, where "replugging" the same device hundreds of times over the course of days of runtime eventually exhausts some internal resource, causing the port to go completely dead until you unbind/bind the xhci device.
Note that if you're not on RPi or some other device with easily usable GPIO to control the relay, you can use any FTDI cable as 4x GPIO, and there are lots of cheap 5V relay breakout boards available.