linux-kernel - [PATCH v3 3/7] PCI: Do not disable memory decoding in pci_reassigndev_resource

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Date:	Thu, 30 Jun 2016 18:53:09 +0800
From:	Yongji Xie <xyjxie@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-doc@...r.kernel.org
Cc:	bhelgaas@...gle.com, alex.williamson@...hat.com, aik@...abs.ru,
	benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
	corbet@....net, warrier@...ux.vnet.ibm.com,
	zhong@...ux.vnet.ibm.com, nikunj@...ux.vnet.ibm.com,
	gwshan@...ux.vnet.ibm.com
Subject: [PATCH v3 3/7] PCI: Do not disable memory decoding in pci_reassigndev_resource_alignment()

We should not disable memory decoding when we reassign alignment
in pci_reassigndev_resource_alignment(). It's meaningless and
have some side effect. For example, some fixup functions such as
quirk_e100_interrupt() read PCI_COMMAND_MEMORY to know whether
the devices has been initialized by the firmware or not. If we
disable memory decoding here, these functions will get a wrong
information that the devices was not initialized by the firmware
which may cause a wrong fixup. Besides, disabling memory decoding
may also break some devices that need to have memory decoding
always-on during probing.

Signed-off-by: Yongji Xie <xyjxie@...ux.vnet.ibm.com>
---
 drivers/pci/pci.c |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6ae02de..6241cfc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4820,7 +4820,6 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
 	int i;
 	struct resource *r;
 	resource_size_t align, size;
-	u16 command;
 
 	/* We should never try to reassign VF's alignment */
 	if (dev->is_virtfn)
@@ -4838,12 +4837,7 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
 		return;
 	}
 
-	dev_info(&dev->dev,
-		"Disabling memory decoding and releasing memory resources.\n");
-	pci_read_config_word(dev, PCI_COMMAND, &command);
-	command &= ~PCI_COMMAND_MEMORY;
-	pci_write_config_word(dev, PCI_COMMAND, command);
-
+	dev_info(&dev->dev, "Releasing memory resources.\n");
 	for (i = 0; i < PCI_BRIDGE_RESOURCES; i++) {
 		r = &dev->resource[i];
 		if (!(r->flags & IORESOURCE_MEM))
-- 
1.7.9.5