Re: [PATCH v5 01/46] usb: gadget: encapsulate endpoint claiming mechanism

[Robert Baldyga]

On 08/20/2015 06:48 PM, Felipe Balbi wrote:
> On Thu, Aug 20, 2015 at 06:28:14PM +0200, Robert Baldyga wrote:
> > Hi Felipe,
> >
> > On 08/20/2015 05:35 PM, Felipe Balbi wrote:
> > [...]
> > > just letting you know that this regresses all gadget drivers making them
> > > try to disable previously disabled endpoints and enable previously
> > > enabled endpoints.
> > >
> > > I have a possible fix (see below) but then it shows a problem on the
> > > host side when using with g_zero (see further below):
> > >
> > > commit 3b8932100aacb6cfbffe288ca93025d8b8430c00
> > > Author: Felipe Balbi <balbi@xxxxxx>
> > > Date:   Wed Aug 19 18:05:27 2015 -0500
> > >
> > >      usb: gadget: fix ep->claimed lifetime
> > >
> > >      In order to fix a regression introduced by commit
> > >      cc476b42a39d ("usb: gadget: encapsulate endpoint
> > >      claiming mechanism") we have to introduce a simple
> > >      helper to check if a particular is enabled or not.
> > >
> > >      After that, we need to move ep->claimed lifetime to
> > >      usb_ep_enable() and usb_ep_disable() since those
> > >      are the only functions which actually enable and
> > >      disable endpoints.
> > >
> > >      A follow-up patch will come to drop all driver_data
> > >      checks from function drivers, since those are, now,
> > >      pointless.
> > >
> > >      Fixes: cc476b42a39d ("usb: gadget: encapsulate endpoint
> > >      	claiming mechanism")
> > >      Cc: Robert Baldyga <r.baldyga@xxxxxxxxxxx>
> > >      Signed-off-by: Felipe Balbi <balbi@xxxxxx>
> > >
> > > diff --git a/drivers/usb/gadget/epautoconf.c b/drivers/usb/gadget/epautoconf.c
> > > index 978435a51038..ad45070cd76f 100644
> > > --- a/drivers/usb/gadget/epautoconf.c
> > > +++ b/drivers/usb/gadget/epautoconf.c
> > > @@ -126,7 +126,6 @@ found_ep:
> > >   	ep->address = desc->bEndpointAddress;
> > >   	ep->desc = NULL;
> > >   	ep->comp_desc = NULL;
> > > -	ep->claimed = true;
> >
> > Removing this line causes autoconfig can return the same endpoint many
> > times. This probably causes problems with g_zero.
> >
> > I will try to fix it ASAP.
>
> I was considering the same thing, but the lifetime of ->claimed doesn't
> look correct to me either way. Note that once the flag is enabled, it
> won't get disabled by most gadget drivers.

And it should not be. This flag is indicator, that endpoint is used by 
some function. It should be set once by usb_ep_autoconfig() and cleared 
by usb_ep_autoconfig_reset().

I wonder what is reason of this enable/disable regression. Maybe the 
problem is that we don't set ep->driver_data to NULL in 
usb_ep_autoconfig_reset() (so far it was done). Does this problem occur 
while gadget is binded to UDC for the first time, or at any next time? 
Unfortunately at this moment I don't have access to my hardware, so it 
will take a moment before I will setup some testing environment.

Thanks,
Robert

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