On Sun, 15 Nov 2009, Sriram V wrote: > Hi, > > I have a couple of questions of re-enumeration of usb devices on > suspend-resume > > I have a USB Device permanently connected to the host controller. > > Upon resume - Should i usb device get re-enumerated? If the host controller lost power was reinitialized during the suspend then yes. Otherwise no. In particular, devices should always get re-enumerated when resuming from hibernation. But when resuming from suspend-to-RAM, it depends on the motherboard. > If so, does Linux choose a different address for accessing it? If the device's firmware hasn't changed then the address remains the same. Otherwise a different address is used. Read Documentation/usb/persist.txt. > If i have a USB harddisk, I am accessing it using a device node say > /dev/sdb1 > The harddisk is mounted as /dev/sdb1. > > Now, i go into suspend and then resume - If i need to re-enumerate the > devices > It could be detected as /dev/sdc1... or something. > > If that is the case i cannot access my harddisk - since im assuming > /dev/sdb1. > > What im seeing here is - My usb device is permanently connected to the usb > host via an external phy. > > When i suspend - i turn off the clocks and upon resume - turn on the clocks > and reset the phy. > > For some time - i am able to access the device, What happens is - The > device gets re-enumerated to some other device node. > > I am not sure if this is a device issue or a resume function issue. > > > Please advice. Enable CONFIG_USB_DEBUG in your kernel and post the dmesg log showing what happens during suspend and resume. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
