Re: [RFC PATCH] Revert "usb: chipidea: udc: .pullup is valid only when vbus is there"

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On Mon, 11 Aug 2014, Michael Grzeschik wrote:

> Hi Alan,
> 
> On Mon, Aug 11, 2014 at 10:28:12AM -0400, Alan Stern wrote:
> > On Mon, 11 Aug 2014, Felipe Balbi wrote:
> > 
> > > On Mon, Aug 11, 2014 at 09:44:05AM -0400, Alan Stern wrote:
> > > > On Mon, 11 Aug 2014, Felipe Balbi wrote:
> > > > 
> > > > > > > I don't know what exactly problem you met, but current pullup dp during loading
> > > > > > > gadget driver behavior is not suitable for webcam and android use case even vbus
> > > > > > > is there.
> > > > > > 
> > > > > > Why not?  What's wrong with it?
> > > > > 
> > > > > g_uvc needs a userspace counterpart. If we connect to the host before
> > > > > userspace is ready, we might connect as a non-usable function.
> > > > 
> > > > Okay, but can't that be fixed in g_uvc?  Have it disable the pullup 
> > > > until the userspace component is ready, then enable the pullup.
> > > 
> > > that might be too late, although propbably not catastrophic.
> > 
> > It looks like the UDC core needs to be improved a little.  Right now, 
> > udc_bind_to_driver() unconditionally calls usb_gadget_connect(), 
> > thereby overriding any calls the gadget driver may have made during its 
> > bind callback.
> > 
> > What we should do instead is call usb_gadget_connect() only if the 
> > gadget driver didn't try to change the pullup setting.
> > 
> 
> I remember last years discussion regarding the usage of
> usb_gadget_deactivate and usb_gadget_activate in composite.c:
> 
> http://markmail.org/message/haqte4elxt5xnuf2

Okay.  I don't really care what approach gets used, so long as the 
final version works properly.

Alan Stern

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