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path: root/drivers/pci/pci-driver.c
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Diffstat (limited to 'drivers/pci/pci-driver.c')
-rw-r--r--drivers/pci/pci-driver.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index bf0cee629b60..099f46cd8e87 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -748,6 +748,18 @@ static int pci_pm_suspend_noirq(struct device *dev)
pci_pm_set_unknown_state(pci_dev);
+ /*
+ * Some BIOSes from ASUS have a bug: If a USB EHCI host controller's
+ * PCI COMMAND register isn't 0, the BIOS assumes that the controller
+ * hasn't been quiesced and tries to turn it off. If the controller
+ * is already in D3, this can hang or cause memory corruption.
+ *
+ * Since the value of the COMMAND register doesn't matter once the
+ * device has been suspended, we can safely set it to 0 here.
+ */
+ if (pci_dev->class == PCI_CLASS_SERIAL_USB_EHCI)
+ pci_write_config_word(pci_dev, PCI_COMMAND, 0);
+
return 0;
}