From: Matthew Garrett <mjg59@srcf.ucam.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Khalid Aziz <khalid.aziz@hp.com>,
linux-kernel@vger.kernel.org, bhelgaas@google.com,
linux-pci@vger.kernel.org
Subject: Re: [PATCH] Disable Bus Master on PCI device shutdown
Date: Wed, 6 Jun 2012 21:09:46 +0100 [thread overview]
Message-ID: <20120606200946.GA11946@srcf.ucam.org> (raw)
In-Reply-To: <87obowxm5s.fsf@xmission.com>
On Wed, Jun 06, 2012 at 12:42:07PM -0700, Eric W. Biederman wrote:
> pci_device_shutdown calls drv->shutdown before calling
> pci_device_disable. Which means that only devices that have trouble
> with this bit being flipped while DMA is ongoing and don't bother
> to stop their own DMA will have a problem.
drv->shutdown should already be quiescing the hardware. If it isn't, it
should be. If it is, what does this patch fix? Many drivers
call pci_enable_device() early enough that they clearly expect the
hardware to be quiescent when they do so, so this really does seem to
simply handle the kexec case without handling any other cases that could
be similarly problematic.
--
Matthew Garrett | mjg59@srcf.ucam.org
next prev parent reply other threads:[~2012-06-06 20:10 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-27 19:00 [PATCH] Disable Bus Master on PCI device shutdown Khalid Aziz
2012-05-03 23:52 ` Bjorn Helgaas
2012-05-04 17:15 ` Bjorn Helgaas
2012-06-06 13:50 ` Matthew Garrett
2012-06-06 16:17 ` Khalid Aziz
2012-06-06 16:27 ` Matthew Garrett
2012-06-06 17:32 ` Khalid Aziz
2012-06-06 17:42 ` Matthew Garrett
2012-06-06 18:07 ` Khalid Aziz
2012-06-06 19:42 ` Eric W. Biederman
2012-06-06 20:09 ` Matthew Garrett [this message]
2012-06-07 17:43 ` Khalid Aziz
2012-06-07 14:21 ` Khalid Aziz
2012-06-06 20:16 ` Myron Stowe
2012-06-06 23:03 ` Khalid Aziz
2012-06-06 23:18 ` Myron Stowe
2012-06-06 20:50 ` Alan Cox
2012-06-07 17:07 ` Andi Kleen
2012-06-07 17:13 ` Alan Cox
2012-06-07 17:36 ` Khalid Aziz
2012-06-07 17:08 ` Andi Kleen
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