Message-ID: <3C76D873.FAA028E0@mandrakesoft.com>
Date: Fri, 22 Feb 2002 18:46:59 -0500
From: Jeff Garzik <jgarzik@mandrakesoft.com>
Organization: MandrakeSoft
MIME-Version: 1.0
To: Andre Hedrick <andre@linuxdiskcert.org>
CC: =?iso-8859-1?Q?G=E9rard?= Roudier <groudier@free.fr>,
        Vojtech Pavlik <vojtech@suse.cz>, Arjan van de Ven <arjanv@redhat.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2.5.5-pre1 IDE cleanup 9
In-Reply-To: <Pine.LNX.4.10.10202221210430.2519-100000@master.linux-ide.org>
Content-Type: text/plain; charset=us-ascii
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Sender: linux-kernel-owner@vger.kernel.org

Andre Hedrick wrote:
> 
> On Fri, 22 Feb 2002, Jeff Garzik wrote:
> 
> > Andre Hedrick wrote:
> > > Also not that ATA/IDE drivers were not using 2.4 PCI API and likewise was
> > > stable for a while.
> >
> > Stable?  Yes.  But it's not modular nor compatible with current efforts
> > like 2.4 cardbus or 2.4 hotplug pci or 2.5 device mode.  If one cannot
> > do
> >       modprobe piix4_ide
> > and have the right things happen automatically, the system is not
> > modular.  If it doesn't use the PCI API, it's implementing CardBus
> > support in a non-standard way if at all.
> 
> Now what happens if you have more than one HOST of the same kind or the
> "SAME HOST" with multiple functions but are really one HOST?
> 
> I do not see how this will handle the problem.
> But obviously I have been to far down making sure the DATA got to platter
> correct and most likely missed a few things. :-/
> 
> > > > This is need for transparented support for cardbus and hotplug PCI, not
> > >
> > > This is HOST level operation not DEVICE, and you do not see the differenc.
> >
> > I do.  I am talking about a HOST api here.
> 
> Okay we are getting some place now, cause what I was reading and seeing in
> the changes registers a DRIVE to the PCI API and not a HOST.

Yes... I think there was some earlier confusion.  PCI API is definitely
an API for registering hosts.

If you have a C structure "struct drive", it may be useful to have a
pointer to struct pci_dev.  That is just a reference from drive back to
the host.  So you could do crazy references like this pseudocode:

  struct pci_dev *host_pci;
  struct ata_host *host_ata;
  struct ata_channel *channel;

  host_pci = cur_drive->pci_dev;
  host_ata = pci_get_drvdata(host_pci);
  channel = &host_ata->channels[cur_drive->channel_number];

These back-references are very useful, and use of a concept like this
may be the source of confusion.

	Jeff


-- 
Jeff Garzik      | "UNIX enhancements aren't."
Building 1024    |           -- says /usr/games/fortune
MandrakeSoft     |
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