[PATCH 1/1] usb: core: Kconfig: refine the description for CONFIG_USB_OTG

[Peter Chen]

> 
> On Tue, May 13, 2014 at 01:11:44PM +0200, Greg KH wrote:
> > On Tue, May 13, 2014 at 10:19:27AM +0800, Peter Chen wrote:
> > > the user should only select it when the board supports HNP and SRP,
> > > it should NOT be selected if the board only supports dual-role
> > > switch through ID pin.
> > >
> > > There is a discussion for it:
> > > http://marc.info/?l=linux-arm-kernel&m=139994896101516&w=2
> > > http://marc.info/?l=linux-usb&m=139994881701504&w=2
> > >
> > > Signed-off-by: Peter Chen <peter.chen at freescale.com>
> > > ---
> > >  drivers/usb/core/Kconfig |   12 +++++++-----
> > >  1 files changed, 7 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
> > > index cb8e991..158048b 100644
> > > --- a/drivers/usb/core/Kconfig
> > > +++ b/drivers/usb/core/Kconfig
> > > @@ -54,13 +54,15 @@ config USB_OTG
> > >  	default n
> > >  	help
> > >  	  The most notable feature of USB OTG is support for a
> > > -	  "Dual-Role" device, which can act as either a device
> > > -	  or a host. The initial role is decided by the type of
> > > -	  plug inserted and can be changed later when two dual
> > > -	  role devices talk to each other.
> > > +	  otg device, which can act as either a device or a host.
> > > +	  The initial role is decided by the type of plug inserted
> > > +	  and can be changed using HNP (Host Negotiation Protocol)
> > > +	  later when two otg devices talk to each other.
> > >
> > >  	  Select this only if your board has Mini-AB/Micro-AB
> > > -	  connector.
> > > +	  connector and supports HNP and SRP (Session Request Protocol).
> > > +	  If the board only supports dual-role switch through ID
> > > +	  pin, this configuration should not be selected.
> >
> > That's really lame.  What happened to our "all modconfig should work"
> > goal?  Why can't you dynamically detect that this is not a config that
> > works and handle it?
> >

If CONFIG_USB_OTG and CONFIG_USB_OTG_WHITELIST are set, most of usb devices
will not work when connect to host for current code.

So, we need a feature flag for hcd and gadget, and set this OTG feature flag
if the platform supports it (using dtb or platform data).

Peter

> > And this is just the OTG "core", not any specific hardware, so why
> > should it matter?
> 
> yeah, I'm with Greg here... we should find a better way to sort this out.
> 
> --
> balbi