PCI: Disable Bus Master only on kexec reboot
Add a flag to tell the PCI subsystem that kernel is shutting down in
preparation to kexec a kernel. Add code in PCI subsystem to use this flag
to clear Bus Master bit on PCI devices only in case of kexec reboot.
This fixes a power-off problem on Acer Aspire V5-573G and likely other
machines and avoids any other issues caused by clearing Bus Master bit on
PCI devices in normal shutdown path. The problem was introduced by
b566a22c2332 ("PCI: disable Bus Master on PCI device shutdown").
This patch is based on discussion at
http://marc.info/?l=linux-pci&m=138425645204355&w=2
Link: https://bugzilla.kernel.org/show_bug.cgi?id=63861
Reported-by: Chang Liu <cl91tp@gmail.com>
Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: stable@vger.kernel.org # v3.5+diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 7edd5c3..25f0bc6 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -19,6 +19,7 @@
#include <linux/cpu.h>
#include <linux/pm_runtime.h>
#include <linux/suspend.h>
+#include <linux/kexec.h>
#include "pci.h"
struct pci_dynid {
@@ -415,12 +416,17 @@
pci_msi_shutdown(pci_dev);
pci_msix_shutdown(pci_dev);
+#ifdef CONFIG_KEXEC
/*
- * Turn off Bus Master bit on the device to tell it to not
- * continue to do DMA. Don't touch devices in D3cold or unknown states.
+ * If this is a kexec reboot, turn off Bus Master bit on the
+ * device to tell it to not continue to do DMA. Don't touch
+ * devices in D3cold or unknown states.
+ * If it is not a kexec reboot, firmware will hit the PCI
+ * devices with big hammer and stop their DMA any way.
*/
- if (pci_dev->current_state <= PCI_D3hot)
+ if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot))
pci_clear_master(pci_dev);
+#endif
}
#ifdef CONFIG_PM