linux-kernel - Re: [PATCH] PCI MSI: Yet another fix for MSI-X with NIU cards, v2

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Date:	Wed, 13 May 2009 14:06:30 +0900
From:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
To:	Matthew Wilcox <matthew@....cx>
CC:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"David S. Miller" <davem@...emloft.net>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI MSI: Yet another fix for MSI-X with NIU cards, v2

Hi David and all,

Sorry, if you have problem with wrong diffstat in patch header
(it was because I hand-fixed the comment in patch), please use
following instead.  Contents are not changed, still v2.

Thanks,
H.Seto


The NIU device refuses to allow accesses to MSI-X registers before MSI-X
is enabled.  This patch fixes the problem by moving the read & write the
mask register (for preserved bits) to after MSI-X is enabled.

Reported-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
---
 drivers/pci/msi.c |   21 ++++++++++++++++++---
 1 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 6f2e629..44085e0 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -455,9 +455,7 @@ static int msix_capability_init(struct pci_dev *dev,
 		entry->msi_attrib.default_irq = dev->irq;
 		entry->msi_attrib.pos = pos;
 		entry->mask_base = base;
-		entry->masked = readl(base + j * PCI_MSIX_ENTRY_SIZE +
-					PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
-		msix_mask_irq(entry, 1);
+		entry->masked = 1;
 
 		list_add_tail(&entry->list, &dev->msi_list);
 	}
@@ -493,6 +491,23 @@ static int msix_capability_init(struct pci_dev *dev,
 	msix_set_enable(dev, 1);
 	dev->msix_enabled = 1;
 
+	/*
+	 * The states of Reserved bits[31:01] of Vector Control for MSI-X
+	 * Table Entries must be 0.  However, for potential future use,
+	 * software must preserve the value of these reserved bits.
+	 * Refer PCI spec 3.0, 6.8.2.9.
+	 *
+	 * Note that there are some device that refuses access to MSI-X
+	 * Table Entries before MSI-X is enabled.  Therefore we do it here. 
+	 */
+	list_for_each_entry(entry, &dev->msi_list, list) {
+		int vector = entry->msi_attrib.entry_nr;
+		entry->masked = readl(base + vector * PCI_MSIX_ENTRY_SIZE +
+					PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
+		/* Make sure it is masked */
+		msix_mask_irq(entry, 1);
+	}
+
 	return 0;
 }
 
-- 
1.6.3

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