Re: Nothing in /sys/class/udc

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On Mon, Sep 3, 2018 at 3:40 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Mon, Sep 03, 2018 at 09:39:14AM +0300, Ranran wrote:
> > Hello,
> >
> > I try to add gadget configfs as described in:
> > https://www.kernel.org/doc/Documentation/usb/gadget_configfs.txt
> > Yet, I find nothing in /sys/class/udc:
> >
> > user@user-VirtualBox:~/tegra$ ls /sys/class/udc/ -al
> > total 0
> > drwxr-xr-x  2 root root 0 Sep  3 00:30 .
> > drwxr-xr-x 58 root root 0 Sep  3 00:30 ..
> >
> > I also don't have dwc2, but dwc3:
> > user@user-VirtualBox:~/tegra$ lsmod | grep dw
> > dwc3                   90112  0
> > ulpi                   16384  1 dwc3
> > udc_core               24576  2 dwc3,libcomposite
> > user@user-VirtualBox:~/tegra$
> >
> > Kernel is 4.4.50.
>
> Why do you think the dwc3 driver will work here?  Do you really have
> this hardware being emulated?
>
Hi,

I check it with Intel's E3900.
In datasheet, I can't find it being described in details in datasheet,
yet being linked with another document ("see Section Little-Endian and
Big-Endian in the DWC SuperSpeed USB 3.0 Controller User Guide" )
https://www.mouser.com/ds/2/612/atom-e3800-family-datasheet-915661.pdf
I have installed module dwc3 and also dwc2 (both compiled as modules),
but nothing appear in /sys/class/udc
I also tried to add all options in device-drivers->usb->usb
gadget->usb peripheral control into kernel, (not as modules, but built
into kernel).
Yet, on checking
ls /sys/class/udc
I only find dummy_udc.0 , and nothing else.

Thank you for any idea,
ranran

> And 4.4.50 is very old, please use a modern kernel please.
>
> thanks,
>
> greg k-h



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