RE: Enabling multiple gadgets on top of composite driver

From: Bhupesh SHARMA
Date: Mon Apr 16 2012 - 04:16:49 EST

Hi Felipe,

> -----Original Message-----
> From: Felipe Balbi [mailto:balbi@xxxxxx]
> Sent: Friday, April 13, 2012 4:29 PM
> To: Bhupesh SHARMA
> Cc: balbi@xxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux-
> usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> stern@xxxxxxxxxxxxxxxxxxx
> Subject: Re: Enabling multiple gadgets on top of composite driver
> On Fri, Apr 13, 2012 at 06:51:26PM +0800, Bhupesh SHARMA wrote:
> > Hi,
> >
> > I have a query regarding enabling multiple gadgets (like g_webcam,
> > g_zero etc..) on top of the Composite driver.
> >
> > My use case is very simple:
> > - I want to expose a USB composite device to a standard USB host,
> where
> > the Composite device supports a webcam gadget + zero gadget +
> some other gadget..
> look at how nokia.c does it.


> > On the older kernels like 2.6.27, this was easily possible, but the
> > latest gadget code doesn't seem to support the same:
> > - I can see that first a 'choicemenu' is provided which allows
> selection of only
> > one gadget at a time.
> Answer M instead of Y to "USB Gadget Drivers"
> > - The "common" stuff like "composite.c", "epautoconfig.c" have
> been included in
> > each f_* function driver (for e.g. f_uvc.c, f_sourcesink.c,
> etc..), so even if
> > I somehow tweak the 'choicemenu' stuff, I get redeclaration
> errors.
> yeah, that still needs to be cleaned up. The story behind that is very
> long.
> > What is the best way to enable multiple gadgets (like g_webcam,
> g_zero
> > etc..) on top of the Composite driver or am I missing something here?
> Either you want multiple gadgets or you want a composite gadget, what
> is it ? If you want a composite gadget, you need to write a small C
> file which combines multiple functions together (see nokia.c), if you
> want multiple gadget drivers, just make them all modules. I always
> compile all gadget drivers as modules and can use any one of them at
> any time.

Thanks for your help.
I need to support multiple functions over a composite gadget. I will now
have a quick look at the 'nokia.c' driver.

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