Date: Tue, 14 Dec 2010 11:29:52 -0800
From: Greg KH <gregkh@suse.de>
To: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>, linux-kernel@vger.kernel.org
Subject: Re: [RFC] bind/unbind uevent
Message-ID: <20101214192952.GA9106@suse.de>
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On Tue, Dec 14, 2010 at 07:26:40PM +0100, Sebastian Ott wrote:
> 
> On Mon, 13 Dec 2010, Greg KH wrote:
> > On Mon, Dec 13, 2010 at 08:27:45PM +0100, Sebastian Ott wrote:
> > > On Wed, 8 Dec 2010, Greg KH wrote:
> > > > On Wed, Dec 08, 2010 at 11:18:27AM +0100, Sebastian Ott wrote:
> > > > > On Tue, 7 Dec 2010, Kay Sievers wrote:
> > > > > > On Tue, Dec 7, 2010 at 19:33, Greg KH <gregkh@suse.de> wrote:
> > > > > > > On Tue, Dec 07, 2010 at 06:29:37PM +0100, Sebastian Ott wrote:
> > > > > > 
> > > > > > >> So I'm searching for a trigger when these attributes are created, or
> > > > > > >> in other words when the device is useable, which I think translates to
> > > > > > >> when a driver is bound to this device.
> > > > > > >
> > > > > > > Again, KOBJ_ADD is the correct one.
> > > > > > >
> > > > > > > If your driver is creating sysfs attributes on its own, that's a bug and
> > > > > > > should be fixed.
> > > > > > 
> > > > > > Sounds a bit like the driver should create its own child device with
> > > > > > its own properties, instead of mangling around with attributes at a
> > > > > > device it binds to.
> > > > > 
> > > > > Yes, I get that feeling too. But I'm talking about existing drivers
> > > > > and I don't think I can change their whole structure.
> > > > 
> > > > It's just a matter of putting the attributes in a table and passing that
> > > > to the bus code the driver registers with.  Only a minor change in the
> > > > driver is needed to resolve this.
> > > 
> > > I don't get it. The current situation is, that our drivers
> > > add attributes to the device they are about to bind with, in
> > > the probe function.
> > 
> > Don't do that, have your _driver_ register the attributes with the bus
> > it is on, then when the binding happens, the attributes will
> > automatically get created for the device before the notification is sent
> > to userspace.  That is the proper proceedure here.
> 
> are you suggesting that these driver specific device attributes should be
> created by the bus code which registers the device?

Yes.

> at this time it is not determinable which driver will bind to the device
> (and therefore which attributes to create), also driver specific data may 
> not be initialized.

{sigh}

Please go _look_ at how the driver model handles this type of thing.  It
does _exactly_ what you want, as we have been doing it for _years_
properly.

thanks,

greg k-h
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