USB: EHCI, OHCI: handover changes
This patch (as887) changes the way ehci-hcd and ohci-hcd handle a loss
of VBUS power during suspend. In order for the USB-persist facility
to work correctly, it is necessary for low- and full-speed devices
attached to a high-speed port to be handed back to the companion
controller during resume processing.
This entails three changes: adding code to ehci-hcd to perform the
handover, removing code from ohci-hcd to turn off ports during
root-hub reinit, and adding code to ohci-hcd to turn on ports during
PCI controller resume. (Other bus glue resume methods for platforms
supporting high-speed controllers would need a similar change, if any
existed.)
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/host/ohci-pci.c b/drivers/usb/host/ohci-pci.c
index ca62cb5..15013f4 100644
--- a/drivers/usb/host/ohci-pci.c
+++ b/drivers/usb/host/ohci-pci.c
@@ -202,6 +202,42 @@
return ret;
}
+#if defined(CONFIG_USB_PERSIST) && (defined(CONFIG_USB_EHCI_HCD) || \
+ defined(CONFIG_USB_EHCI_HCD_MODULE))
+
+/* Following a power loss, we must prepare to regain control of the ports
+ * we used to own. This means turning on the port power before ehci-hcd
+ * tries to switch ownership.
+ *
+ * This isn't a 100% perfect solution. On most systems the OHCI controllers
+ * lie at lower PCI addresses than the EHCI controller, so they will be
+ * discovered (and hence resumed) first. But there is no guarantee things
+ * will always work this way. If the EHCI controller is resumed first and
+ * the OHCI ports are unpowered, then the handover will fail.
+ */
+static void prepare_for_handover(struct usb_hcd *hcd)
+{
+ struct ohci_hcd *ohci = hcd_to_ohci(hcd);
+ int port;
+
+ /* Here we "know" root ports should always stay powered */
+ ohci_dbg(ohci, "powerup ports\n");
+ for (port = 0; port < ohci->num_ports; port++)
+ ohci_writel(ohci, RH_PS_PPS,
+ &ohci->regs->roothub.portstatus[port]);
+
+ /* Flush those writes */
+ ohci_readl(ohci, &ohci->regs->control);
+ msleep(20);
+}
+
+#else
+
+static inline void prepare_for_handover(struct usb_hcd *hcd)
+{ }
+
+#endif /* CONFIG_USB_PERSIST etc. */
+
#ifdef CONFIG_PM
static int ohci_pci_suspend (struct usb_hcd *hcd, pm_message_t message)
@@ -241,7 +277,10 @@
static int ohci_pci_resume (struct usb_hcd *hcd)
{
set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
- usb_hcd_resume_root_hub(hcd);
+
+ /* FIXME: we should try to detect loss of VBUS power here */
+ prepare_for_handover(hcd);
+
return 0;
}