Date: Thu, 10 Feb 2005 10:12:55 -0800
From: Greg KH <greg@kroah.com>
To: Adam Belay <abelay@novell.com>
Cc: rml@novell.com, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] add driver matching priorities
Message-ID: <20050210181255.GC8683@kroah.com>
References: <1106951404.29709.20.camel@localhost.localdomain> <20050210084113.GZ32727@kroah.com> <1108055918.3423.23.camel@localhost.localdomain>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1108055918.3423.23.camel@localhost.localdomain>
User-Agent: Mutt/1.5.6i
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2530
Lines: 58

On Thu, Feb 10, 2005 at 12:18:37PM -0500, Adam Belay wrote:
> On Thu, 2005-02-10 at 00:41 -0800, Greg KH wrote:
> > On Fri, Jan 28, 2005 at 05:30:04PM -0500, Adam Belay wrote:
> > > Hi,
> > > 
> > > This patch adds initial support for driver matching priorities to the
> > > driver model.  It is needed for my work on converting the pci bridge
> > > driver to use "struct device_driver".  It may also be helpful for driver
> > > with more complex (or long id lists as I've seen in many cases) matching
> > > criteria. 
> > > 
> > > "match" has been added to "struct device_driver".  There are now two
> > > steps in the matching process.  The first step is a bus specific filter
> > > that determines possible driver candidates.  The second step is a driver
> > > specific match function that verifies if the driver will work with the
> > > hardware, and returns a priority code (how well it is able to handle the
> > > device).  The bus layer could override the driver's match function if
> > > necessary (similar to how it passes *probe through it's layer and then
> > > on to the actual driver).
> > > 
> > > The current priorities are as follows:
> > > 
> > > enum {
> > > 	MATCH_PRIORITY_FAILURE = 0,
> > > 	MATCH_PRIORITY_GENERIC,
> > > 	MATCH_PRIORITY_NORMAL,
> > > 	MATCH_PRIORITY_VENDOR,
> > > };
> > > 
> > > let me know if any of this would need to be changed.  For example, the
> > > "struct bus_type" match function could return a priority code.
> > > 
> > > Of course this patch is not going to be effective alone.  We also need
> > > to change the init order.  If a driver is registered early but isn't the
> > > best available, it will be bound to the device prematurely.  This would
> > > be a problem for carbus (yenta) bridges.
> > > 
> > > I think we may have to load all in kernel drivers first, and then begin
> > > matching them to hardware.  Do you agree?  If so, I'd be happy to make a
> > > patch for that too.
> > 
> > I think the issue that Al raises about drivers grabbing devices, and
> > then trying to unbind them might be a real problem.
> 
> I agree.  Do you think registering every in-kernel driver before probing
> hardware would solve this problem?

This doesn't work for any vendor kernel as they build all drivers as
modules :(

thanks,

greg k-h
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/