Hello list and Ran, I've some more observations. Firstly, I have to set the dwc3 mode to peripheral directly. Checking the code I was unable to find what actually allows you to select the mode if specifying OTG. I have devices in /sys/class/udc and they function properly via configfs when plugged into a USB2 only port. If I plug them into a superspeed port I get nothing in dmesg on the host side. At first, I did get a response on the host, in the form of: [591550.770819] usb 1-1.2: new full-speed USB device number 76 using xhci_hcd [591550.870962] usb 1-1.2: device descriptor read/64, error -32 [591551.078865] usb 1-1.2: device descriptor read/64, error -32 [591551.286875] usb 1-1.2: new full-speed USB device number 77 using xhci_hcd [591551.386873] usb 1-1.2: device descriptor read/64, error -32 [591551.594859] usb 1-1.2: device descriptor read/64, error -32 [591551.703160] usb 1-1-port2: attempt power cycle However now I get no driver activity when binding the UDC in configfs or loading or unloading the respective modules. Kernel is 5.7.15 w/ patches. It doesn't seem like a fried the port or tripped a polyfuse, the port still works after attempting USB3 device mode. On Thu, Sep 17, 2020, at 10:42 PM, Ran Wang wrote: > Hi Sid, > > > -----Original Message----- > > From: Sid Spry <sid@xxxxxxx> > > Sent: Friday, September 18, 2020 11:08 AM > > To: Ran Wang <ran.wang_1@xxxxxxx> > > Cc: linux-usb@xxxxxxxxxxxxxxx > > Subject: Re: Enabling Device DWC3 Device Mode > > > > Thanks Ran. I took a look at the document, if you or anyone else can weigh in > > I'd appreciate it. The platform devices seem to be active, see below. > > So you want to use 'otg' or 'preripheral'? The SW flows is a little bit > different (in dwc3/core.c) > If you want otg, I guess module solution would not be good. But I have > no idea how to enable > mass storage gadget in build-in way, to be honest. So you could try > ethernet gadget which > doesn't require passing parameters, it works on my part. > > > Starting at line 767. It's a lot sparser, but the dr_mode is there. I feel I should > > note that despite the lack of devices in /sys/class/udc I have nodes in > > /sys/bus/platform/drivers/dwc3: > > > > # ls /sys/bus/platform/drivers/dwc3 > > bind fe800000.usb fe900000.usb module uevent unbind > > > > > One of the example in DTS is > > > arch/arm64/boot/dts/freescale/fsl-lx2160a.dtsi > > > and arch/arm64/boot/dts/freescale/fsl-lx2160a-rdb.dts, and you need to > > > manually update it by following above doc to enable device mode. > > > > > > > The document linked is relevant beginning page 445. The above dts settings > > seem appropriate and I have the necessary kernel configuration enabled. Any > > relevant drivers are modules. > > > > I'm not really sure how to diagnose it from here. Any help is appreciated. > > Parsing property 'dr_mode' is the key to control driver logic path. > > I think you could begin with drivers/usb/dwc3/core.c, see what happen > in dwc3_core_init_mode() > which handling role switching (host/peripheral/otg) in calling > dwc3_probe() > if you have made sure all kernel configuration had been done correctly, > such as (ethernet gadget): > CONFIG_USB_DWC3=y > CONFIG_USB_DWC3_DUAL_ROLE=y > CONFIG_USB_GADGET=y > CONFIG_USB_CONFIGFS=y > CONFIG_USB_ETH=y > > With dr_mode=peripheral (or otg), it should work (if above dwc3_probe() > encountered no error). > I will pursue this in more detail so I don't need to reboot to change dwc3 mode but didn't find any relevant code path for otg -> device from userspace. I'll try debugging later. Sid.
