linux-kernel - Re: [2.6.24-rc6-mm1]Build failure in drivers/net/ehea/ehea

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Message-ID: <20080207221712.GC19310@kroah.com>
Date:	Thu, 7 Feb 2008 14:17:12 -0800
From:	Greg KH <greg@...ah.com>
To:	Christoph Raisch <RAISCH@...ibm.com>
Cc:	akpm@...ux-foundation.org, Jan-Bernd Themann <THEMANN@...ibm.com>,
	linux-kernel@...r.kernel.org, Nathan Lynch <ntl@...ox.com>,
	ossthema@...ux.vnet.ibm.com, sam@...nborg.org,
	Sudhir Kumar <skumar@...ux.vnet.ibm.com>,
	Joachim Fenkes <FENKES@...ibm.com>
Subject: Re: [2.6.24-rc6-mm1]Build failure in drivers/net/ehea/ehea_main.c

On Tue, Jan 29, 2008 at 03:20:20PM +0100, Christoph Raisch wrote:
> Greg KH <greg@...ah.com> wrote on 29.01.2008 14:23:09:
> 
> > On Tue, Jan 29, 2008 at 11:12:40AM +0100, Jan-Bernd Themann wrote:
> ...
> > > The sym-link is not gereated automatically as the device for portX is
> added
> > > to the eHEA device (as subnode) where the eHEA device is not a bus.
> >
> > Then please fix that, no other driver has this kind of problem, right?
> > Are you just passing the wrong "device" to the networking subsystem?
> >
> > > If this sym-link is of interest (which I guess is the case as most
> devices
> > > have it) we have to create it somehow.
> >
> > Why would you have to do this by hand?  What makes this driver so unique
> > in the kernel that it would have to do this?  We have lots of other
> > multi-port ethernet drivers today without this issue, right?
> >
> > confused,
> >
> > greg k-h
> 
> well, the major difference is hea is not PCI.

What is it?  It has to live on some kind of bus, right?

> All PCI cards we checked have a 1:1 relationship between PCI function (PCI
> config space) and a single ethernet port.
> Even if the same Ethernet chip has two ports, it shows up as two separate
> adapters from the PCI perspective (two PCI entries in /sys/bus/pci/devices
> 
> host:/ # ls -l /sys/bus/pci/devices/0000\:c8\:01.0/
> total 0
> lrwxrwxrwx 1 root root      0 2008-01-28 14:59 bus -> ../../../../bus/pci
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 class
> -rw-r--r-- 1 root root    256 2008-01-28 14:59 config
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 device
> -r--r--r-- 1 root root   4096 2008-01-29 14:26 devspec
> lrwxrwxrwx 1 root root      0 2008-01-28 14:59 driver ->
> ../../../../bus/pci/drivers/e1000
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 irq
> -r--r--r-- 1 root root   4096 2008-01-29 14:26 local_cpus
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 modalias
> lrwxrwxrwx 1 root root      0 2008-01-29 14:26 net:eth1 ->
> ../../../../class/net/eth1
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 resource
> ....
> host:/ # ls -l /sys/bus/pci/devices/0000\:c8\:01.1/
> total 0
> lrwxrwxrwx 1 root root      0 2008-01-28 14:59 bus -> ../../../../bus/pci
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 class
> -rw-r--r-- 1 root root    256 2008-01-28 14:59 config
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 device
> -r--r--r-- 1 root root   4096 2008-01-29 14:29 devspec
> lrwxrwxrwx 1 root root      0 2008-01-28 14:59 driver ->
> ../../../../bus/pci/drivers/e1000
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 irq
> -r--r--r-- 1 root root   4096 2008-01-29 14:29 local_cpus
> -r--r--r-- 1 root root   4096 2008-01-28 14:59 modalias
> lrwxrwxrwx 1 root root      0 2008-01-29 14:29 net:eth2 ->
> ../../../../class/net/eth2
> ...
> 
> These pci functions corresponds to a
> /sys/bus/ibmebus/devices/789D.001.XXXXXX-P1/port0
> and
> /sys/bus/ibmebus/devices/789D.001.XXXXXX-P1/port1
> 
> The busdriver currently does not find out, how many ports are in a
> /sys/bus/ibmebus/devices/789D.001.XXXXXX-P1.
> This is up to the hardware specific driver responsible for ehea or ehca.
> Think of a PCI card where the PCI busdriver
> can not determine how many ports are implemented on the card.
> 
> How should this be mapped to /sys ?
> 
> Should we try to "flatten" the ports to something like
> /sys/bus/ibmebus/devices/789D.001.XXXXXX-P1
> /sys/bus/ibmebus/devices/789D.001.XXXXXX-P1_port0
> /sys/bus/ibmebus/devices/789D.001.XXXXXX-P1_port1
> ...which means physical hierarchy information would look a bit strange,
> but could be the simpler one.

No.  Why have a separate "port" device for every ethernet port?  What
keeps you from just creating the different network devices for your
device, and pointing the parent to the same 789D.001.XXXXXX-P1 device?

Lots of PCI devices hang "class devices" off of them all the time, why
would this be any different from that?

I think you all are trying to make this more complex than it really is
:)

thanks,

greg k-h
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