On Mon, 25 Sep 2017, David Tulloh wrote: > Hi, > > I have been trying to get a UVC gadget running through configfs and > wired in to dummy_hcd. > > I have largely been following the instructions from the Tizen wiki. > https://wiki.tizen.org/USB/Linux_USB_Layers/Configfs_Composite_Gadget/Usage_eq._to_g_webcam.ko > > However I am getting a hard lockup, I believe when device is started. > The system does not respond to any commands, including SYSRQ. > > A bash script I have been executing to set it all up is attached, as is the log. > > I am running in a VM against v4.14-rc2. I have the same issues with > v4.13 and with the recent setup_timer() patch set. The v4.10 kernel > had other issues which have since been corrected. > > The last log lines are: > + echo dummy_udc.0 > [ 92.086000] udc dummy_udc.0: registering UDC driver [g1] > [ 92.086620] configfs-gadget gadget: adding 'uvc'/ffff9f6ab8a965f0 > to config 'c'/ffff9f6aba715520 > [ 92.087544] configfs-gadget gadget: uvc_function_bind > [ 92.089110] dummy_hcd dummy_hcd.0: port status 0x00010101 has changes > ~~~ end of transmission ~~~ > > > Is there anything obvious that I have done wrong or an area I should > start looking? > > I have very little kernel experience but am happy to poke at things > with GDB like a small child until something happens. However with the > size of the code base I would appreciate some pointers on where to > start poking. Does uvc use isochronous transfers? I assume it would, since it's a video protocol. dummy-hcd does not support isochronous. I don't know what would happen if you tried it, but one way or another it would not work the way you want. Of course, you might be facing a different problem. 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
