On Sat, 21 Nov 2015, Patrick Shirkey wrote: > Hi, > > I have a libusb (USB-2.0_ tree with the following layout: > > HOST (USB 2.0) -> 5 port hub (master) -> 5 x 10 port hub -> 50 x USB devices > > It is a 50 unit mobile device charger and also enables USB data comms to > the individual devices. Each node is independently powered. The devices > are all the same model/make. I know this is a relative corner case for USB > 2.0 standard but that is another story. > > Is it possible to reset the ports on the 5 port hub (master) individually > with libusb or some other system level command? I have written a program (for Linux only; it doesn't use libusb) that issues a reset to a single device: http://marc.info/?l=linux-usb&m=126944503308931&w=2 You can use this to reset each of the 10-port hubs in turn. Or even to reset the 5-port hub. > Here's the scenario: > > When I insert usb devices with the entire chain connected I see varying > results for the number of devices detected by the HOST. Sometimes 15 are > detected, sometimes 34, 22, 5, etc... However If I disconnect the cables > for the 10 port hubs to the 5 port master hub before I insert all the > devices and then connect each 10 port hub one at a time with a delay to > ensure all the devices on that hub are detected all 50 devices are > detected on the host. It sounds like there may be something wrong with that 5-port hub. This sort of thing _should_ work reliably. > So I would like to know if there is a method to disable/enable the ports > on the 5 port master without resetting the entire bus or causing the sub > nodes/hubs to "bounce" their connections. I don't know of any way to disable an individual port on a hub. Note that disable is different from reset. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
