[patch 004/104] USB: fix SB700 usb subsystem hang bug

From: Greg KH
Date: Wed Dec 03 2008 - 14:51:33 EST

2.6.27-stable review patch. If anyone has any objections, please let us know.

From: Andiry Xu <andiry.xu@xxxxxxx>

commit b09bc6cbae4dd3a2d35722668ef2c502a7b8b093 upstream.

This patch is required for AMD SB700 south bridge revision A12 and A13 to avoid
USB subsystem hang symptom. The USB subsystem hang symptom is observed when the
system has multiple USB devices connected to it. In some cases a USB hub may be
required to observe this symptom.

This patch works around the problem by correcting the internal register setting
that will help by changing the behavior of the internal logic to avoid the
USB subsystem hang issue. The change in the behavior of the logic does not
impact the normal operation of the USB subsystem.

Reported-by: Volker Armin Hemmann <volker.armin.hemmann@xxxxxxxxxxxxxxx>
Tested-by: Volker Armin Hemmann <volker.armin.hemmann@xxxxxxxxxxxxxxx>
Signed-off-by: Andiry Xu <andiry.xu@xxxxxxx>
Signed-off-by: Libin Yang <libin.yang@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

drivers/usb/host/ehci-pci.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -66,6 +66,8 @@ static int ehci_pci_setup(struct usb_hcd
struct ehci_hcd *ehci = hcd_to_ehci(hcd);
struct pci_dev *pdev = to_pci_dev(hcd->self.controller);
+ struct pci_dev *p_smbus;
+ u8 rev;
u32 temp;
int retval;

@@ -166,6 +168,25 @@ static int ehci_pci_setup(struct usb_hcd
pci_write_config_byte(pdev, 0x4b, tmp | 0x20);
+ /* SB700 old version has a bug in EHCI controller,
+ * which causes usb devices lose response in some cases.
+ */
+ if (pdev->device == 0x4396) {
+ p_smbus = pci_get_device(PCI_VENDOR_ID_ATI,
+ NULL);
+ if (!p_smbus)
+ break;
+ rev = p_smbus->revision;
+ if ((rev == 0x3a) || (rev == 0x3b)) {
+ u8 tmp;
+ pci_read_config_byte(pdev, 0x53, &tmp);
+ pci_write_config_byte(pdev, 0x53, tmp | (1<<3));
+ }
+ pci_dev_put(p_smbus);
+ }
+ break;


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/