Hi,

Alan Stern <[email protected]> writes:
>> I have been trying to get a UVC gadget running through configfs and
>> wired in to dummy_hcd.
>> 
>> I have largely been following the instructions from the Tizen wiki.
>> https://wiki.tizen.org/USB/Linux_USB_Layers/Configfs_Composite_Gadget/Usage_eq._to_g_webcam.ko
>> 
>> However I am getting a hard lockup, I believe when device is started.
>> The system does not respond to any commands, including SYSRQ.
>> 
>> A bash script I have been executing to set it all up is attached, as is the 
>> log.
>> 
>> I am running in a VM against v4.14-rc2. I have the same issues with
>> v4.13 and with the recent setup_timer() patch set. The v4.10 kernel
>> had other issues which have since been corrected.
>> 
>> The last log lines are:
>> + echo dummy_udc.0
>> [   92.086000] udc dummy_udc.0: registering UDC driver [g1]
>> [   92.086620] configfs-gadget gadget: adding 'uvc'/ffff9f6ab8a965f0
>> to config 'c'/ffff9f6aba715520
>> [   92.087544] configfs-gadget gadget: uvc_function_bind
>> [   92.089110] dummy_hcd dummy_hcd.0: port status 0x00010101 has changes
>> ~~~ end of transmission ~~~
>> 
>> 
>> Is there anything obvious that I have done wrong or an area I should
>> start looking?
>> 
>> I have very little kernel experience but am happy to poke at things
>> with GDB like a small child until something happens. However with the
>> size of the code base I would appreciate some pointers on where to
>> start poking.
>
> Does uvc use isochronous transfers?  I assume it would, since it's a 
> video protocol.

yes, it does :-)

> dummy-hcd does not support isochronous.  I don't know what would happen 

really? Then why is it registering iso endpoints to the gadget layer?

static const struct {
        const char *name;
        const struct usb_ep_caps caps;
} ep_info[] = {
#define EP_INFO(_name, _caps) \
        { \
                .name = _name, \
                .caps = _caps, \
        }

        /* everyone has ep0 */
        EP_INFO(ep0name,
                USB_EP_CAPS(USB_EP_CAPS_TYPE_CONTROL, USB_EP_CAPS_DIR_ALL)),
        /* act like a pxa250: fifteen fixed function endpoints */
        EP_INFO("ep1in-bulk",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_BULK, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep2out-bulk",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_BULK, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep3in-iso",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ISO, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep4out-iso",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ISO, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep5in-int",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_INT, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep6in-bulk",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_BULK, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep7out-bulk",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_BULK, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep8in-iso",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ISO, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep9out-iso",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ISO, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep10in-int",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_INT, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep11in-bulk",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_BULK, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep12out-bulk",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_BULK, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep13in-iso",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ISO, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep14out-iso",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ISO, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep15in-int",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_INT, USB_EP_CAPS_DIR_IN)),
        /* or like sa1100: two fixed function endpoints */
        EP_INFO("ep1out-bulk",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_BULK, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep2in-bulk",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_BULK, USB_EP_CAPS_DIR_IN)),
        /* and now some generic EPs so we have enough in multi config */
        EP_INFO("ep3out",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep4in",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep5out",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep6out",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep7in",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep8out",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep9in",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep10out",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep11out",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep12in",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep13out",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_OUT)),
        EP_INFO("ep14in",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_IN)),
        EP_INFO("ep15out",
                USB_EP_CAPS(USB_EP_CAPS_TYPE_ALL, USB_EP_CAPS_DIR_OUT)),

#undef EP_INFO
};

> if you tried it, but one way or another it would not work the way you 
> want.

if that's really the case, then maybe we should remove all the iso
endpoints from dummy. Right?

-- 
balbi

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