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Message-ID: <20070425112146.16d076c0@the-village.bc.nu>
Date: Wed, 25 Apr 2007 11:21:46 +0100
From: Alan Cox <alan@...rguk.ukuu.org.uk>
To: Tejun Heo <htejun@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
"Berck E. Nash" <flyboy@...il.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Jeff Garzik <jeff@...zik.org>, linux-ide@...r.kernel.org
Subject: Re: 2.6.21-rc7-mm1 BUG at kernel/sched-clock.c:175
init_sched_clock()
> static void ahci_freeze(struct ata_port *ap)
> {
> + void __iomem *mmio = ap->host->iomap[AHCI_PCI_BAR];
> void __iomem *port_mmio = ahci_port_base(ap);
>
> /* turn IRQ off */
> writel(0, port_mmio + PORT_IRQ_MASK);
> +
> + /* clear IRQ pending bit */
> + writel(1 << ap->port_no, mmio + HOST_IRQ_STAT);
Neither of those two are going to help in all cases. They are PCI writes
to mmio so they are posted. You don't know they hit the device until a
read cycle coming back has completed, so you need to read something after
doing this to be sure.
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