On Tue, Dec 6, 2016 at 7:52 PM, John Youn <John.Youn@xxxxxxxxxxxx> wrote: > On 12/6/2016 5:48 PM, John Stultz wrote: >> Hey John, >> Just wanted to send this by you, as it seems something is >> slightly off with the GOTGCTL state when removing a otg adapter >> cable. The following seems to work around the issue I'm seeing. >> >> >> When removing a USB-A to USB-otg adapter cable, we get a change >> status irq, and then in dwc2_conn_id_status_change, we >> erroniously see the GOTGCTL_CONID_B flag set. This causes us to > > This is the correct behavior for an OTG controller. When you unplug a > cable or plug in the B end of a cable, the ID pin floats, indicating > it is a B-Device. > > When you plug in an A-cable, which is what your adapter is, it will > ground the pin, meaning A-device. Hrm... So normally, when I plug in the gadget cable into the OTG port, I see the change_status irq comes in and the function sees: dwc2 f72c0000.usb: gotgctl=4010000 dwc2 f72c0000.usb: gotgctl.b.conidsts=1 dwc2 f72c0000.usb: Do port resume before switching to device mode dwc2 f72c0000.usb: dwc2_hsotg_enqueue_setup: failed queue (-11) dwc2 f72c0000.usb: new device is high-speed dwc2 f72c0000.usb: new device is high-speed dwc2 f72c0000.usb: new device is high-speed dwc2 f72c0000.usb: new address 37 configfs-gadget gadget: high-speed config #1: b Then when I unplug the cable: dwc2 f72c0000.usb: gotgctl=2200000 dwc2 f72c0000.usb: gotgctl.b.conidsts=0 usb 1-1: reset high-speed USB device number 13 using dwc2 When I plug in the OTG to USB-A adapter cable w/ a mouse plugged in (note I see no change interrupt): usb 1-1: USB disconnect, device number 13 usb 1-1: new low-speed USB device number 14 using dwc2 input: Logitech USB Optical Mouse as /devices/platform/soc/f72c0000.usb/usb1/1-1/1-1:1.0/0003:046D:C058.0003/input/input3 hid-generic 0003:046D:C058.0003: input,hidraw0: USB HID v1.11 Mouse [Logitech USB Optical Mouse] on usb-f72c0000.usb-1/input0 Then unplugging the OTG to USB-A adapter cable w/ mouse: dwc2 f72c0000.usb: gotgctl=4010000 dwc2 f72c0000.usb: gotgctl.b.conidsts=1 dwc2 f72c0000.usb: Do port resume before switching to device mode dwc2 f72c0000.usb: Waiting for Peripheral Mode, Mode=Host <here we get stuck in the loop until it finishes, unless using the patch from this thread> usb 1-1: USB disconnect, device number 14 dwc2 f72c0000.usb: gotgctl=2200000 dwc2 f72c0000.usb: gotgctl.b.conidsts=0 usb 1-1: new high-speed USB device number 15 using dwc2 hub 1-1:1.0: USB hub found hub 1-1:1.0: 3 ports detected So I only get the change irq when: * I plug in a micro-usb-B cable for gadget mode * I remove the micro-usb-B cable being used for gadget mode * I remove a OTG to USB-A adapter One slight quirk, is that I don't always see the change irq when removing the OTG to USB, as if I plug in a highspeed mass-storage device, instead of the low-speed mouse, I don't see the change interrupt and the device shows up and disappears the same as when I plug into the normal USB-A host ports on the board. >> get stuck in the "while (!dwc2_is_device_mode(hsotg))" loop, >> spitting out "Waiting for Peripheral Mode, Mode=Host" warnings >> until it fails out many seconds later. > > This is weird. Once the ID pin goes to B, the core should become a > peripheral and this should be reflected in the status registers. > >> >> This patch works around the issue by re-reading the GOTGCTL >> state to check if the GOTGCTL_CONID_B is still set and if not >> restarting the change status logic. > > This also seems weird. The connector id status shouldn't go back to A, > assuming you've left the cable unplugged. So I suspect this has something to do with the way the USB-A host ports on the board are wired up. As removing the usb-b plug seems to switch the device back into A mode. One quirk with this board is that the USB-A ports on the board do not function if anything is in the OTG/B plug (which is frustrating to use at times). Guodong or Chen Yu understand the hardware details a bit better, and might be able to explain more if you need more information. > Is the controller supposed to work in both peripheral and host modes? I certainly hope so! >> I suspect this isn't the best solution, but it seems to work >> well for me. >> > > The workaround seems fine, but still, this indicates that something > wrong is going on somwhere. Yea. While I'm ok with some of these workarounds, I'd be happier to figure out what the proper thing should be. > You can add my ack: > > Acked-by: John Youn <johnyoun@xxxxxxxxxxxx> Many thanks! -john -- 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
