linux-kernel - [PATCH] PCI: Retry BARs restoration for Type 0 headers only

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Date:	Mon, 16 Apr 2012 22:35:49 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Mikko Vinni <mmvinni@...oo.com>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Allen Kay <allen.m.kay@...el.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH] PCI: Retry BARs restoration for Type 0 headers only

From: Rafael J. Wysocki <rjw@...k.pl>

Some shortcomings introduced into pci_restore_state() by commit
26f41062f28d ("PCI: check for pci bar restore completion and
retry") have been fixed by recent commit ebfc5b802fa76 ("PCI: Fix
regression in pci_restore_state(), v3"), but that commit treats
all PCI devices as those with Type 0 configuration headers.  That
is not entirely correct, because Type 1 and Type 2 headers have
different layouts.  In particular, the area occupied by BARs in
Type 0 config headers contains the secondary status register in
Type 1 ones and it doesn't make sense to retry the restoration of
that register even if the value read back from it after a write is
not the same as the written one (it very well may be different).

For this reason, make pci_restore_state() only retry the restoration
of BARs for Type 0 config headers.  This effectively makes it behave
as before commit 26f41062f28d for all header types except for Type 0.

Tested-by: Mikko Vinni <mmvinni@...oo.com>
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 drivers/pci/pci.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

Index: linux/drivers/pci/pci.c
===================================================================
--- linux.orig/drivers/pci/pci.c
+++ linux/drivers/pci/pci.c
@@ -1015,13 +1015,17 @@ void pci_restore_state(struct pci_dev *d
 	pci_restore_pcie_state(dev);
 	pci_restore_ats_state(dev);

-	pci_restore_config_space(dev, 10, 15, 0);
-	/*
-	 * The Base Address register should be programmed before the command
-	 * register(s)
-	 */
-	pci_restore_config_space(dev, 4, 9, 10);
-	pci_restore_config_space(dev, 0, 3, 0);
+	if (dev->hdr_type == PCI_HEADER_TYPE_NORMAL) {
+		pci_restore_config_space(dev, 10, 15, 0);
+		/*
+		 * The Base Address register should be programmed before the
+		 * command register(s)
+		 */
+		pci_restore_config_space(dev, 4, 9, 10);
+		pci_restore_config_space(dev, 0, 3, 0);
+	} else {
+		pci_restore_config_space(dev, 0, 15, 0);
+	}

 	pci_restore_pcix_state(dev);
 	pci_restore_msi_state(dev);
--
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