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Subject: RE: [RFC/PATCH]reconfigure MSI registers after resume
Date: Thu, 1 Sep 2005 08:20:50 -0700
Message-ID: <C7AB9DA4D0B1F344BF2489FA165E502409A1201A@orsmsx404.amr.corp.intel.com>
Thread-Topic: [RFC/PATCH]reconfigure MSI registers after resume
thread-index: AcWui6U/IkAGxTgySmius/YA36ZZAwAeqAEQ
From: "Nguyen, Tom L" <tom.l.nguyen@intel.com>
To: "Greg KH" <greg@kroah.com>, "Li, Shaohua" <shaohua.li@intel.com>
Cc: "lkml" <linux-kernel@vger.kernel.org>, "akpm" <akpm@osdl.org>
Sender: linux-kernel-owner@vger.kernel.org
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On Wednesday, August 31, 2005 2:44 PM Greg KH wrote:
>>On Thu, Aug 18, 2005 at 01:35:46PM +0800, Shaohua Li wrote:
>> Hi,
>> It appears pci_enable_msi doesn't reconfigure msi registers if it
>> successfully look up a msi for a device. It assumes the data and
address
>> registers unchanged after calling pci_disable_msi. But this isn't
always
>> true, such as in a suspend/resume circle. In my test system, the
>> registers unsurprised become zero after a S3 resume. This patch fixes
my
>> problem, please look at it. MSIX might have the same issue, but I
>> haven't taken a close look.

> Tom, any comments on this?

In the cases of suspend/resume, a device driver needs to restore its PCI
configuration space registers, which include the MSI/MSI-X capability
structures if a device uses MSI/MSI-X. I think reconfiguring MSI
data/address each time a driver calls pci_enable_msi may not be
necessary.

Thanks,
Tom
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