OHCI: work around for nVidia shutdown problem

This patch (as1417) fixes a problem affecting some (or all) nVidia
chipsets.  When the computer is shut down, the OHCI controllers
continue to power the USB buses and evidently they drive a Reset
signal out all their ports.  This prevents attached devices from going
to low power.  Mouse LEDs stay on, for example, which is disconcerting
for users and a drain on laptop batteries.

The fix involves leaving each OHCI controller in the OPERATIONAL state
during system shutdown rather than putting it in the RESET state.
Although this nominally means the controller is running, in fact it's
not doing very much since all the schedules are all disabled.  However
there is ongoing DMA to the Host Controller Communications Area, so
the patch also disables the bus-master capability of all PCI USB
controllers after the shutdown routine runs.

The fix is applied only to nVidia-based PCI OHCI controllers, so it
shouldn't cause problems on systems using other hardware.  As an added
safety measure, in case the kernel encounters one of these running
controllers during boot, the patch changes quirk_usb_handoff_ohci()
(which runs early on during PCI discovery) to reset the controller
before anything bad can happen.

Reported-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Tested-by: Pali Rohár <pali.rohar@gmail.com>
CC: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 7 deletions

diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
index 83b5f9cea85a..464ed977b45d 100644
--- a/drivers/usb/host/pci-quirks.c
+++ b/drivers/usb/host/pci-quirks.c
@@ -169,6 +169,7 @@ static int __devinit mmio_resource_enabled(struct pci_dev *pdev, int idx)
 static void __devinit quirk_usb_handoff_ohci(struct pci_dev *pdev)
 {
         void __iomem *base;
+        u32 control;
 
         if (!mmio_resource_enabled(pdev, 0))
                 return;
@@ -177,10 +178,14 @@ static void __devinit quirk_usb_handoff_ohci(struct pci_dev *pdev)
         if (base == NULL)
                 return;
 
+        control = readl(base + OHCI_CONTROL);
+
 /* On PA-RISC, PDC can leave IR set incorrectly; ignore it there. */
-#ifndef __hppa__
-{
-        u32 control = readl(base + OHCI_CONTROL);
+#ifdef __hppa__
+#define OHCI_CTRL_MASK          (OHCI_CTRL_RWC | OHCI_CTRL_IR)
+#else
+#define OHCI_CTRL_MASK          OHCI_CTRL_RWC
+
         if (control & OHCI_CTRL_IR) {
                 int wait_time = 500; /* arbitrary; 5 seconds */
                 writel(OHCI_INTR_OC, base + OHCI_INTRENABLE);
@@ -194,13 +199,12 @@ static void __devinit quirk_usb_handoff_ohci(struct pci_dev *pdev)
                         dev_warn(&pdev->dev, "OHCI: BIOS handoff failed"
                                         " (BIOS bug?) %08x\n",
                                         readl(base + OHCI_CONTROL));
-
-                /* reset controller, preserving RWC */
-                writel(control & OHCI_CTRL_RWC, base + OHCI_CONTROL);
         }
-}
 #endif
 
+        /* reset controller, preserving RWC (and possibly IR) */
+        writel(control & OHCI_CTRL_MASK, base + OHCI_CONTROL);
+
         /*
          * disable interrupts
          */