From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
Date: Thu, 28 Oct 2010 15:09:49 +0100
Subject: [PATCH 1/6] Realview PCIX support - add main support module code
In-Reply-To: <201010202316.33540.arnd@arndb.de>
References: <20101020125554.22199.78597.stgit@e102602-lin.cambridge.arm.com>
	<20101020130253.22199.48589.stgit@e102602-lin.cambridge.arm.com>
	<201010202316.33540.arnd@arndb.de>
Message-ID: <20101028140949.GE3122@n2100.arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wed, Oct 20, 2010 at 11:16:32PM +0200, Arnd Bergmann wrote:
> > +{
> > +	u32 mode;
> > +	u32 config_addr;
> > +
> > +	writel(0x000307F7, PCIX_UNIT_BASE + PCI_PERRSTAT); /* clear error bit */
> > +	writew(0xfb30, PCIX_UNIT_BASE + PCI_STATUS);	   /* error bit clear */
> 
> I would guess that you need locking here, two drivers might simultaneously be
> accessing config space on different CPUs, or you might have kernel preemption
> enabled and get preempted between the register accesses.

pci config accesses are serialized by a global pci_lock raw spinlock,
which disables IRQs.