On Mon, Jun 17, 2019 at 5:40 AM Felipe Balbi <balbi@xxxxxxxxxx> wrote: > > Lianwei Wang <lianwei.wang@xxxxxxxxx> writes: > > > The udc and gadget device will be deleted when udc device is > > disconnected and the related function will be unbind with it. > > > > But if the configfs is not deleted, then the function object > > will be kept and the bound status is kept true. > > > > Then after udc device is connected again and a new udc and > > gadget objects will be created and passed to bind interface. > > But because the bound is still true, the new gadget is not > > updated to netdev and a previous freed gadget will be used > > in netdev after bind. > > > > To fix this using after freed issue, always set the gadget > > object to netdev in bind interface. > > > > Signed-off-by: Lianwei Wang <lianwei.wang@xxxxxxxxx> > > I can't actually understand what's the problem here. The gadget is not > deleted when we disconnect the cable. > > -- > balbi The issue was observed with a dual-role capable USB controller (e.g. Intel XHCI controller), which has the ability to switch role between host and device mode. The gadget is deleted when we switch role to device mode from host mode. See below log: # echo p > /sys/devices/pci0000:00/0000:00:15.1/intel-cht-otg.0/mux_state #(4.4) [ 41.170891] intel-cht-otg intel-cht-otg.0: p: set PERIPHERAL mode [ 41.171895] dwc3 dwc3.0.auto: DWC3 OTG Notify USB_EVENT_VBUS [ 41.187420] dwc3 dwc3.0.auto: dwc3_resume_common [ 41.191192] usb 1-1: USB disconnect, device number 3 [ 41.191284] usb 1-1.1: USB disconnect, device number 4 [ 41.218958] usb 1-1.5: USB disconnect, device number 5 [ 41.238117] android_work: sent uevent USB_STATE=CONFIGURED [ 41.240572] android_work: sent uevent USB_STATE=DISCONNECTED [ 41.263285] platform dabr_udc.0: unregister gadget driver 'configfs-gadget' [ 41.263413] configfs-gadget gadget: unbind function 'Function FS Gadget'/ffff8801db049e38 [ 41.263969] configfs-gadget gadget: unbind function 'cdc_network'/ffff8801d8897400 [ 41.325943] dabridge 1-1.5:1.0: Port 3 VBUS OFF [ 41.720957] dabr_udc deleted [ 41.721097] dabridge 1-5 deleted The UDC and gadget will be deleted after switch role to device mode. And they will be created as new object when switching back to host mode. At this time the bind in function driver (e.g. f_ncm) will not set the new gadget. For kernel 4.19+, the role switch command will be: echo "device" > /sys/class/usb_role/intel_xhci_usb_sw-role-switch/role The latest Intel role switch kernel driver can be found here: https://elixir.bootlin.com/linux/v5.2-rc5/source/drivers/usb/roles/intel-xhci-usb-role-switch.c Thanks, Lianwei
