USB: ohci: quirk AMD prefetch for USB 1.1 ISO transfer

The following patch in the driver is required to avoid USB 1.1 device
failures that may occur due to requests from USB OHCI controllers may
be overwritten if the latency for any pending request by the USB
controller is very long (in the range of milliseconds).

Signed-off-by: Libin Yang <libin.yang@amd.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/usb/host/ohci-pci.c b/drivers/usb/host/ohci-pci.c
index d2ba04dd785e..b8a1148f248e 100644
--- a/drivers/usb/host/ohci-pci.c
+++ b/drivers/usb/host/ohci-pci.c
@@ -177,6 +177,13 @@ static int ohci_quirk_amd700(struct usb_hcd *hcd)
                 return 0;
 
         pci_read_config_byte(amd_smbus_dev, PCI_REVISION_ID, &rev);
+
+        /* SB800 needs pre-fetch fix */
+        if ((rev >= 0x40) && (rev <= 0x4f)) {
+                ohci->flags |= OHCI_QUIRK_AMD_PREFETCH;
+                ohci_dbg(ohci, "enabled AMD prefetch quirk\n");
+        }
+
         if ((rev > 0x3b) || (rev < 0x30)) {
                 pci_dev_put(amd_smbus_dev);
                 amd_smbus_dev = NULL;
@@ -262,6 +269,19 @@ static void amd_iso_dev_put(void)
 
 }
 
+static void sb800_prefetch(struct ohci_hcd *ohci, int on)
+{
+        struct pci_dev *pdev;
+        u16 misc;
+
+        pdev = to_pci_dev(ohci_to_hcd(ohci)->self.controller);
+        pci_read_config_word(pdev, 0x50, &misc);
+        if (on == 0)
+                pci_write_config_word(pdev, 0x50, misc & 0xfcff);
+        else
+                pci_write_config_word(pdev, 0x50, misc | 0x0300);
+}
+
 /* List of quirks for OHCI */
 static const struct pci_device_id ohci_pci_quirks[] = {
         {