To: Matthew Wilcox <matthew@wil.cx>, John Partridge <johnip@sgi.com>
Cc: "Richard B. Johnson" <jmodem@AbominableFirebug.com>,
       "Michael S. Tsirkin" <mst@mellanox.co.il>, linux-kernel@vger.kernel.org,
       linux-ia64@vger.kernel.org, jeff@garzik.org, openib-general@openib.org,
       linux-pci@atrey.karlin.mff.cuni.cz, David Miller <davem@davemloft.net>
Subject: Re: Ordering between PCI config space writes and MMIO reads?
References: <20061024214724.GS25210@parisc-linux.org>
	<adar6wxbcwt.fsf@cisco.com> <20061024223631.GT25210@parisc-linux.org>
	<20061024.154347.77057163.davem@davemloft.net>
	<aday7r4a3d7.fsf@cisco.com> <adad588tijq.fsf@cisco.com>
	<20061031195312.GD5950@mellanox.co.il>
	<019301c6fd2c$044d7010$0732700a@djlaptop>
	<20061031204717.GG26964@parisc-linux.org>
From: Roland Dreier <rdreier@cisco.com>
Date: Tue, 31 Oct 2006 14:30:13 -0800
In-Reply-To: <20061031204717.GG26964@parisc-linux.org> (Matthew Wilcox's message of "Tue, 31 Oct 2006 13:47:17 -0700")
Message-ID: <ada4ptkt8y2.fsf@cisco.com>
User-Agent: Gnus/5.1007 (Gnus v5.10.7) XEmacs/21.4.18 (linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 847
Lines: 19

 > I'm beginning to think Michael Tsirkin has the only solution to this
 > -- architectures need to check that their hardware blocks until the
 > config write completion has occurred (and if not, simulate that it has
 > in software).

OK, I guess I'm convinced.  The vague language in the base PCI 3.0
spec about "dependencies" made me think that a read of a config
register had to wait until all previous writes to the same register
are done.  So I'll drop this patch for now.

John, you'll need to try and come up with a way to solve this in the
Altix implementation of pci_write_config_xxx().

 - R.
-
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/