On Tue, 9 Oct 2018, Alan Stern wrote: > On Mon, 8 Oct 2018, Christoph Groth wrote: > > > On Sun, 7 Oct 2018, Alan Stern wrote: > > > > > On Fri, 5 Oct 2018, Christoph Groth wrote: > > > > > > > I would be grateful for hints on how solve or further debug this > > > > problem. > > > > > > A good start would be to post a usbmon trace showing what happens > > > when you plug in the Garmin device. Also you could post the dmesg > > > log, because it might contain some useful information about what > > > happened during the failure. > > > > Thanks, Alan. Here are two sets of logs: > > > > (...) > > The difference between the two usbmon traces is this request in the > x220 trace: > > ffff9d69e4b579c0 293665112 S Ci:1:018:0 s 80 06 03ee 0000 0400 1024 < > ffff9d69e4b579c0 294668236 C Ci:1:018:0 -2 0 > > This is a Get-String-Descriptor request for string index 0xee, which > is reserved by Microsoft as their OS String Descriptor. Evidently the > Garmin does not like this request, because it freezes up and the > request has to be cancelled. After that the Garmin doesn't do > anything, whereas by contrast on the cubie it disconnects after about > 4 seconds and then reconnects with a different set of descriptors > (those of a proper mass-storage device). Thanks! So, in a nutshell, this is another bug in the Foretrex firmware? They make really nice hardware, but why don't they realize that abandoning their totally closed firmware development model would actually profit them? > As far as I know the kernel does not send this request for the OS > String Descriptor automatically, so most likely it comes from some > program running on the x220 and not on the cubie. One good candidate > is usb_modeswitch, but it could be something else. > > You might get more information in the kernel log if you turn on the > usbfs_snoop module parameter for the usbcore module. Uninstalling usb_modeswitch didn't help, so I enabled usbfs_snoop and saw in dmesg that the command mtp-probe is launched when the device is plugged in. Uninstalling this one did the trick, but it also means that I can no longer transfer files to and from Android phones. (Perhaps there's a way to inhibit mtp-probe only for the Garmin device.) One last question: is the 'lsusb -v' freeze that I observed anything that should be reported? Or is it just fair for lsusb to block upon waiting for a device that froze? IIRC, I wasn't even able to 'kill -9' it, but eventually it went away. Thanks again, Christoph
