On Thu, Dec 31, 2015 at 4:43 PM, Charles Lepple <[email protected]> wrote:
> Thanks for the libusb version numbers. By the way, which version of NUT > are you using? > > nut-2.7.3 > On Dec 31, 2015, at 6:23 PM, Nicholas Leippe <[email protected]> wrote: > > > > I haven't cracked open the nut sources yet, but am curious why it should > fail to open the usb device after already succeeding many times. > > Could it be a USB power management issue? Or simply opening it too many > times somehow breaks it? > > One major difference between the initial startup of usbhid-ups and when it > tries to reconnect: in the former case, the USB stack has had time to fully > start up all of the kernel-side drivers. > > When usbhid-ups attempts to claim the UPS HID interface for the first time > after the UPS is plugged in (or has reattached itself), the kernel USB HID > driver causes an EBUSY return code ("failed to claim USB device: Device or > resource busy"). Usually, the EBUSY code goes away after usbhid-ups tells > the kernel to relinquish the interface (line 271 [*]), but in your case, it > is possible that the USB HID driver hasn't completely started up. This > might explain the "failed to detach kernel driver from USB device: No such > file or directory" error. > > [*] > https://github.com/networkupstools/nut/blob/master/drivers/libusb.c#L271 > > Since dmesg now shows timestamps, you might want to check to see the time > delta between when the UPS is first detected, and when USB-related messages > stop appearing. It's about half a second on this Raspberry Pi (which > incidentally is now running a 4.1.x kernel): > > [ 2.893909] usb 1-1.2: new low-speed USB device number 4 using dwc_otg > [ 3.041108] usb 1-1.2: New USB device found, idVendor=09ae, > idProduct=3016 > [ 3.050101] usb 1-1.2: New USB device strings: Mfr=3, Product=1, > SerialNumber=5 > [ 3.059367] usb 1-1.2: Product: TRIPP LITE UPS > [ 3.065704] usb 1-1.2: Manufacturer: Tripp Lite > [ 3.558046] hid-generic 0003:09AE:3016.0001: hiddev0,hidraw0: USB HID > v1.11 Device [Tripp Lite TRIPP LITE UPS] on usb-20980000.usb-1.2/input0 > > Note that NUT does not use the kernel USB HID drivers, which is why it has > to detach those drivers to allow libusb to connect. > > Other than the reconnection attempts, usbhid-ups only fully opens the UPS > USB device once. > This is then what confuses me, because it *works* and then dies. If it opens it only once, then why would it fail opening it again--wouldn't it just hold it open and continue to work? It's never failing to start, it's failing to continue working.
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