[PATCH bugfix 3.9] PCI: Don't try to disable Bus Master ondisconnected PCI devices

From: Konstantin Khlebnikov
Date: Thu Mar 14 2013 - 10:49:45 EST

This is fix for commit 7897e6022761ace7377f0f784fca059da55f5d71 from v3.9-rc1
("PCI: Disable Bus Master unconditionally in pci_device_shutdown()")
in turn that was fix for b566a22c23327f18ce941ffad0ca907e50a53d41 from v3.5-rc1
("PCI: disable Bus Master on PCI device shutdown")

Unfortunately fixing one bug uncovers another:
->shutdown() callback might switch device to deep sleep state.
PCI config space no longer available after that.

Link: https://lkml.org/lkml/2013/3/12/529
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Reported-and-Tested-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
drivers/pci/pci-driver.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 1fa1e48..79277fb 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -390,9 +390,10 @@ static void pci_device_shutdown(struct device *dev)

* Turn off Bus Master bit on the device to tell it to not
- * continue to do DMA
+ * continue to do DMA. Don't touch devices in D3cold or unknown states.
- pci_clear_master(pci_dev);
+ if (pci_dev->current_state <= PCI_D3hot)
+ pci_clear_master(pci_dev);

#ifdef CONFIG_PM

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