On Sat, 29 Oct 2011, OBD wrote: > On 29 October 2011 12:40, Neeraj Jakhar <neeraj.jakhar@xxxxxxxxx> wrote: > > On 26 October 2011 21:43, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > >> > >> Try one more experiment: Collect two equivalent usbmon traces, one from > >> each of the computers. �And this time, unload ehci-hcd before starting > >> the trace. �That just might have some effect. �Perhaps comparing the > >> two traces will show something. �Although I doubt it -- this really > >> does look like a low-level problem, like the sort of thing that happens > >> when a device doesn't have quite enough power. > > > > Alan, sorry for a delayed response. I was caught up in a few things. > > > > I tried unloading the ehci_hcd on the laptop on which this modem is > > working. However, there is nothing coming up in either dmesg or usbmon > > output on plugging in the modem. In fact, even the lsusb command fails > > with the following output: > > > > $ lsusb > > unable to initialize libusb: -99 > > > > Just to clarify, ohci_hcd was loaded all this while. Yes, sorry, that's my fault. I forgot that the working laptop doesn't have an OHCI controller. So on that laptop you should keep ehci-hcd loaded. > Sorry for multiple mails (I hope I am not making too many enemies on > this mailing list :), but, > > Surely enough on the laptop on which modem was not working, after > unloading ohci_hcd nothing appears in dmesg and usbmon output on > plugging in the modem. And ehci_hcd was loaded all this while. But what happens on this non-working laptop if ehci-hcd is removed? You should see something when ohci-hcd is loaded or unloaded. And when ohci-hcd is loaded, you should see something when the modem is plugged in or unplugged. Please post the dmesg log for these experiments. If possible, configure your kernel with CONFIG_USB_DEBUG. 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
