Hi Felipe, On Thursday 24 January 2013 16:42:50 Felipe Balbi wrote: > On Thu, Jan 24, 2013 at 03:35:58PM +0100, Michael Grzeschik wrote: > > On Thu, Jan 24, 2013 at 03:21:37PM +0100, Laurent Pinchart wrote: > > > On Thursday 24 January 2013 14:54:01 Michael Grzeschik wrote: > > > > On Thu, Jan 24, 2013 at 12:02:12PM +0100, Laurent Pinchart wrote: > > > > > On Thursday 24 January 2013 11:22:02 Michael Grzeschik wrote: > > > > > > The current implementation of the composite framework connects the > > > > > > gadget function to the device-controller at kernel boottime. > > > > > > > > > > > > It's possible that the userspace application, which handles the > > > > > > enumeration requests of the gadget, starts with high latency when > > > > > > the host did already gave up to detect the gadget. In that case > > > > > > the gadget-application will not work in the first case. > > > > > > > > > > This shouldn't happen, as the UVC gadget driver should start > > > > > disconnected (it calls usb_function_deactive() in > > > > > uvc_function_bind()). If the host can enumerate the gadget before > > > > > the application starts it would then likely be a device controller > > > > > driver bug, not a UVC gadget driver bug. > > > > > > > > Unlikely this is not the case, as usb_gadget_probe_driver triggers an > > > > usb_gadget_connect() right after driver->bind() was called. > > > > > > Indeed, for new-style UDC that's correct. > > > > > > Isn't that an issue with the framework ? I would expect gadget drivers > > > to be able to start disconnected. > > > > That probably is. But it might only be a problem for gadgets with > > userspace components which handle ep0 requests. For other gadgets, which > > are not as dynamic as an webcam, it might be enough to have its > > enumeration handled in kernel and start right on. > > > > That needs further discussion. Therefore my patch is an RFC and a simple > > solution to ship arround that issue. Should we take it though? > > Framework will take care of it, but other controllers need to be fixed > up first so they don't connect their pullup directly. > > We're getting close to that, though. Give me another merge window and > gadget drivers will be required to manage pullup. Thanks :-) -- Regards, Laurent Pinchart
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