[RFC PATCH 1/1] xhci: pci: power off roothub ports in hibernate poweroff_late stage

[Mathias Nyman <mathias.nyman@linux.intel.com>]

Power off roothub ports in hibernate S4 poweroff_late stage to avoid
self-powered usb devices from surviving in U3 suspended state into
next reboot. Bootloader/firmware can't handle usb ports in U3, and
will timeout, causing extra delay during reboot/restore from S4.

Only turn off ports if xhci isn't capable of waking up from S4, as
turning off port power will disable remote wake for connected devices.

This is a bit of a hack, we create a custom non-constant dev_pm_ops
strucure for xhci-pci driver where we first copy the standard
usb_hcd_pci_pm_ops content, and then add the poweroff_late callback
to turn of port power for xhci-pci

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci-hub.c |  4 ++--
 drivers/usb/host/xhci-pci.c | 32 +++++++++++++++++++++++++++++++-
 drivers/usb/host/xhci.h     |  2 ++
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index c54f2bc23d3f..dc404107f4d9 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -652,8 +652,8 @@ struct xhci_hub *xhci_get_rhub(struct usb_hcd *hcd)
  * It will release and re-aquire the lock while calling ACPI
  * method.
  */
-static void xhci_set_port_power(struct xhci_hcd *xhci, struct usb_hcd *hcd,
-				u16 index, bool on, unsigned long *flags)
+void xhci_set_port_power(struct xhci_hcd *xhci, struct usb_hcd *hcd, u16 index,
+			 bool on, unsigned long *flags)
 	__must_hold(&xhci->lock)
 {
 	struct xhci_hub *rhub;
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index fac9492a8bda..89c4c3f07a99 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -85,6 +85,7 @@
 static const char hcd_name[] = "xhci_hcd";
 
 static struct hc_driver __read_mostly xhci_pci_hc_driver;
+static struct dev_pm_ops xhci_hcd_pci_pm_ops;
 
 static int xhci_pci_setup(struct usb_hcd *hcd);
 
@@ -630,6 +631,32 @@ static int xhci_pci_resume(struct usb_hcd *hcd, bool hibernated)
 	return retval;
 }
 
+static int xhci_pci_poweroff_late(struct device *dev)
+{
+	struct pci_dev          *pci_dev = to_pci_dev(dev);
+	struct usb_hcd          *hcd = pci_get_drvdata(pci_dev);
+	struct xhci_hcd		*xhci = hcd_to_xhci(hcd);
+	unsigned long		flags;
+	int			i;
+
+	if (!device_may_wakeup(dev)) {
+		spin_lock_irqsave(&xhci->lock, flags);
+
+		/* Power off USB2 ports*/
+		for (i = 0; i < xhci->usb2_rhub.num_ports; i++)
+			xhci_set_port_power(xhci, xhci->main_hcd, i, false,
+					    &flags);
+		/* Power off USB3 ports*/
+		for (i = 0; i < xhci->usb3_rhub.num_ports; i++)
+			xhci_set_port_power(xhci, xhci->shared_hcd, i, false,
+					    &flags);
+
+		spin_unlock_irqrestore(&xhci->lock, flags);
+	}
+
+	return 0;
+}
+
 static void xhci_pci_shutdown(struct usb_hcd *hcd)
 {
 	struct xhci_hcd		*xhci = hcd_to_xhci(hcd);
@@ -685,7 +712,7 @@ static struct pci_driver xhci_pci_driver = {
 	.shutdown = 	usb_hcd_pci_shutdown,
 #ifdef CONFIG_PM
 	.driver = {
-		.pm = &usb_hcd_pci_pm_ops
+		.pm = &xhci_hcd_pci_pm_ops
 	},
 #endif
 };
@@ -697,6 +724,9 @@ static int __init xhci_pci_init(void)
 	xhci_pci_hc_driver.pci_suspend = xhci_pci_suspend;
 	xhci_pci_hc_driver.pci_resume = xhci_pci_resume;
 	xhci_pci_hc_driver.shutdown = xhci_pci_shutdown;
+
+	xhci_hcd_pci_pm_ops = usb_hcd_pci_pm_ops;
+	xhci_hcd_pci_pm_ops.poweroff_late = xhci_pci_poweroff_late;
 #endif
 	return pci_register_driver(&xhci_pci_driver);
 }
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 0bd76c94a4b1..28aaf031f9a8 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -2196,6 +2196,8 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue, u16 wIndex,
 int xhci_hub_status_data(struct usb_hcd *hcd, char *buf);
 int xhci_find_raw_port_number(struct usb_hcd *hcd, int port1);
 struct xhci_hub *xhci_get_rhub(struct usb_hcd *hcd);
+void xhci_set_port_power(struct xhci_hcd *xhci, struct usb_hcd *hcd, u16 index,
+			 bool on, unsigned long *flags);
 
 void xhci_hc_died(struct xhci_hcd *xhci);
 
-- 
2.25.1