Date: Wed, 11 Jun 2014 14:36:27 -0500
From: Felipe Balbi <balbi@ti.com>
To: Peter Chen <peter.chen@freescale.com>
CC: Felipe Balbi <balbi@ti.com>, Greg KH <gregkh@linuxfoundation.org>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Matt Porter <matt.porter@linaro.org>
Subject: Re: Disable bus's drivers_autoprobe before rootfs has mounted
Message-ID: <20140611193627.GA19366@saruman.home>
Reply-To: <balbi@ti.com>
References: <20140611021439.GA25082@shlinux1.ap.freescale.net>
 <20140611041000.GB15184@kroah.com>
 <20140611043507.GA30126@saruman.home>
 <20140611032956.GC25082@shlinux1.ap.freescale.net>
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On Wed, Jun 11, 2014 at 11:29:57AM +0800, Peter Chen wrote:
> On Tue, Jun 10, 2014 at 11:35:07PM -0500, Felipe Balbi wrote:
> > Hi,
> >=20
> > On Tue, Jun 10, 2014 at 09:10:00PM -0700, Greg KH wrote:
> > > > Let's take USB peripheral as an example, there is a device for
> > > > udc, and a device driver for usb gadget driver, at default, we want
> > > > the device to be bound to driver automatically, this is what
> > > > we have done now. But if there are more than one udcs and gadget
> > > > drivers (eg one B port for mass storage, another B port for usb eth=
ernet),
> > > > the user may want to have specific binding (eg, udc-0 -> mass stora=
ge,
> > > > udc-1 -> usb ethernet), so the binding will be established
> > > > after rootfs has mounted. (This feature is implementing)
> > >=20
> > > Then there better be a way to describe this on the kernel command line
> > > (i.e. module paramaters), right?  Which is a total mess, why not just
> > > not bind anything in this case and let the user pick what they want?
> >=20
> > you can also blacklist all gadget drivers and manually probe them or -
> > get this - you can refrain from using gadget drivers and use libusbg to
> > build the gadget drivers out of raw usb functions, then bind them to the
> > UDC of your liking.
> >=20
>=20
> I am just worried if we change the behaviour of using gadget driver,
> can it be accepted by user? If you think it can be accepted if we can
> have some docs, we can implement manually binding for gadget driver
> from now on.

user shouldn't have to deal with direct module insertion/removal (unless
he's a developer and actually *wants* to do that). Docs are already in
tree. The entire configfs interface has been documented, it's based on
those documents that Matt started writing libusbg.

--=20
balbi

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