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To: Andi Kleen <ak@suse.de>
Cc: Andrew Grover <andy.grover@gmail.com>, Jeff Garzik <jgarzik@pobox.com>,
       Greg KH <gregkh@suse.de>, "David S. Miller" <davem@davemloft.net>,
       tom.l.nguyen@intel.com, linux-pci@atrey.karlin.mff.cuni.cz,
       linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] PCI: remove access to pci_[enable|disable]_msi()
 for drivers - take 2
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From: Roland Dreier <roland@topspin.com>
Date: Wed, 08 Jun 2005 08:57:22 -0700
In-Reply-To: <20050608133503.GT23831@wotan.suse.de> (Andi Kleen's message of
 "Wed, 8 Jun 2005 15:35:03 +0200")
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    Andi> I think we should have the right (default MSI) API by
    Andi> default.  If we wait 5 years we end up with lots of mess in
    Andi> the drivers.

I agree that we should get the API correct as soon as we can.  However
I would argue that one property of the correct API would be that
changing the default from MSI turned off to MSI turned on should not
affect the API.

I like Jeff's suggestion of rolling more common code into
pci_enable_device().  However I'm not sure if this fixes the MSI mess
completely -- there may be some devices where the driver wants to test
interrupt generation and disable MSI if it fails.  However this may be
enough of a special case that we can just add a flag to those
particular drivers so that users can manually control the use of MSI.

 - R.