From mboxrd@z Thu Jan  1 00:00:00 1970
From: willy@linux.intel.com (Matthew Wilcox)
Date: Fri, 27 Jul 2012 16:30:51 -0400
Subject: [PATCH] NVMe: Add a character device for each nvme device
In-Reply-To: <20120727192100.GA2247@kroah.com>
References: <1343407458-29909-1-git-send-email-keith.busch@intel.com>
 <20120727181212.GM22985@linux.intel.com>
 <20120727182546.GA23874@kroah.com>
 <20120727190821.GO22985@linux.intel.com>
 <20120727192100.GA2247@kroah.com>
Message-ID: <20120727203051.GQ22985@linux.intel.com>

On Fri, Jul 27, 2012@12:21:00PM -0700, Greg KH wrote:
> > > Also, why are you creating your own class?  Can't this just be a misc
> > > device?  And if you want to create your own class, please don't, use a
> > > bus, as that is what is really happening here, right?  We are trying to
> > > move away from using 'struct class' wherever possible (one of these days
> > > we'll just remove it...)
> > 
> > What we're trying to achieve here is to create one character device
> > per NVMe controller that gets plugged in.  Each NVMe controller is-a
> > PCI function.  The reason we're trying to do this is so that we can send
> > commands to the NVMe controller, even when there is no storage present
> > (eg a drive is shipped from the factory with no configured storage).
> > 
> > So we have no particular desire to create a new struct class, or struct
> > bus.  If we can create a misc device per PCIe function that's bound to our
> > driver, that's great!  Can you recommend a driver that does this already?
> 
> I don't think there is one, but it shouldn't be that hard to just create
> a 'struct misdevice' for each one of the devices you want to create,
> would it?
> 
> But, as you really are a "specific type", a bus_type might be overkill,
> so the original use of device_create() should be fine.  Just be sure to
> fix the parent pointer issue, and you should be fine, right?

Works for me.  I don't think we're going to have any software that
depends on it being a class or a bus, so it's easy to change later.
All we really care about is /dev/nvmeN being created.