Hi, Wesley Cheng wrote: > Hi linux-usb members! > > I was looking at seeing how the DWC3 drivers are handling the USB cable > disconnect routine (VBUS low situation) when there is no UDC binded. Is > the below behavior expected? > > 1. Enumerate device w/ host. > 2. Gadget is unbinded > - echo "" > /sys/kernel/config/usb_gadget/g1/UDC > 3. Disconnect the USB cable (VBUS low) > 4. No dwc3_gadget_disconnect_interrupt() seen (since controller is > halted from step#1) I think you mean after step#2? > 5. Runtime PM autosuspend fails due to "dwc->connected" being true > (cleared in dwc3_gadget_disconnect_interrupt()) This is probably a mishap in the dwc3 driver. When the function driver is unregistered, the pullup() callback will halt the controller. This is a soft-disconnect, and dwc->connected should be false. > 6. Gadget binded > - echo udc_name > /sys/kernel/config/usb_gadget/g1/UDC After this step, the device will still remain disconnected. > 7. No runtime suspend until cable is plugged in and out ... until the reset and connection done interrupt telling the driver that the device is now connected. > > This would be problematic for devices which have to reliably enter > suspend. I just wanted to see if this is a scenario which has been > considered? Seems odd that we would still keep the controller out of > low power if there was no cable connected. > This should be a simple fix. Would you create a patch for this? Thanks, Thinh
