Merge tag 'for-usb-next-2012-05-18' of git://git.kernel.org/pub/scm/linux/kernel/git/sarah/xhci into usb-next

xhci: Link PM and bug fixes for 3.5.

Hi Greg,

Here's the final Link Power Management patches, along with a couple of bug
fixes that have been sitting in my queue.  I've fixed all the comments that
Alan and Andiry had on the Link PM patches, so I think they're ready to go.

Sarah Sharp

12 files changed, 1329 insertions, 11 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index b32ccb461019..f2a120eea9d4 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1664,6 +1664,7 @@ static struct usb_driver acm_driver = {
 #ifdef CONFIG_PM
 	.supports_autosuspend = 1,
 #endif
+	.disable_hub_initiated_lpm = 1,
 };
 
 /*
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 631bb952d0f6..ea8b304f0e85 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -1034,6 +1034,7 @@ static struct usb_driver wdm_driver = {
 	.post_reset =	wdm_post_reset,
 	.id_table =	wdm_ids,
 	.supports_autosuspend = 1,
+	.disable_hub_initiated_lpm = 1,
 };
 
 module_usb_driver(wdm_driver);
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index f6f81c85c5cf..f536aebc958e 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -288,6 +288,7 @@ static int usb_probe_interface(struct device *dev)
 	struct usb_device *udev = interface_to_usbdev(intf);
 	const struct usb_device_id *id;
 	int error = -ENODEV;
+	int lpm_disable_error;
 
 	dev_dbg(dev, "%s\n", __func__);
 
@@ -324,6 +325,25 @@ static int usb_probe_interface(struct device *dev)
 	if (driver->supports_autosuspend)
 		pm_runtime_enable(dev);
 
+	/* If the new driver doesn't allow hub-initiated LPM, and we can't
+	 * disable hub-initiated LPM, then fail the probe.
+	 *
+	 * Otherwise, leaving LPM enabled should be harmless, because the
+	 * endpoint intervals should remain the same, and the U1/U2 timeouts
+	 * should remain the same.
+	 *
+	 * If we need to install alt setting 0 before probe, or another alt
+	 * setting during probe, that should also be fine.  usb_set_interface()
+	 * will attempt to disable LPM, and fail if it can't disable it.
+	 */
+	lpm_disable_error = usb_unlocked_disable_lpm(udev);
+	if (lpm_disable_error && driver->disable_hub_initiated_lpm) {
+		dev_err(&intf->dev, "%s Failed to disable LPM for driver %s\n.",
+				__func__, driver->name);
+		error = lpm_disable_error;
+		goto err;
+	}
+
 	/* Carry out a deferred switch to altsetting 0 */
 	if (intf->needs_altsetting0) {
 		error = usb_set_interface(udev, intf->altsetting[0].
@@ -338,6 +358,11 @@ static int usb_probe_interface(struct device *dev)
 		goto err;
 
 	intf->condition = USB_INTERFACE_BOUND;
+
+	/* If the LPM disable succeeded, balance the ref counts. */
+	if (!lpm_disable_error)
+		usb_unlocked_enable_lpm(udev);
+
 	usb_autosuspend_device(udev);
 	return error;
 
@@ -361,7 +386,7 @@ static int usb_unbind_interface(struct device *dev)
 	struct usb_driver *driver = to_usb_driver(dev->driver);
 	struct usb_interface *intf = to_usb_interface(dev);
 	struct usb_device *udev;
-	int error, r;
+	int error, r, lpm_disable_error;
 
 	intf->condition = USB_INTERFACE_UNBINDING;
 
@@ -369,6 +394,13 @@ static int usb_unbind_interface(struct device *dev)
 	udev = interface_to_usbdev(intf);
 	error = usb_autoresume_device(udev);
 
+	/* Hub-initiated LPM policy may change, so attempt to disable LPM until
+	 * the driver is unbound.  If LPM isn't disabled, that's fine because it
+	 * wouldn't be enabled unless all the bound interfaces supported
+	 * hub-initiated LPM.
+	 */
+	lpm_disable_error = usb_unlocked_disable_lpm(udev);
+
 	/* Terminate all URBs for this interface unless the driver
 	 * supports "soft" unbinding.
 	 */
@@ -402,6 +434,10 @@ static int usb_unbind_interface(struct device *dev)
 	intf->condition = USB_INTERFACE_UNBOUND;
 	intf->needs_remote_wakeup = 0;
 
+	/* Attempt to re-enable USB3 LPM, if the disable succeeded. */
+	if (!lpm_disable_error)
+		usb_unlocked_enable_lpm(udev);
+
 	/* Unbound interfaces are always runtime-PM-disabled and -suspended */
 	if (driver->supports_autosuspend)
 		pm_runtime_disable(dev);
@@ -442,17 +478,29 @@ int usb_driver_claim_interface(struct usb_driver *driver,
 				struct usb_interface *iface, void *priv)
 {
 	struct device *dev = &iface->dev;
+	struct usb_device *udev;
 	int retval = 0;
+	int lpm_disable_error;
 
 	if (dev->driver)
 		return -EBUSY;
 
+	udev = interface_to_usbdev(iface);
+
 	dev->driver = &driver->drvwrap.driver;
 	usb_set_intfdata(iface, priv);
 	iface->needs_binding = 0;
 
 	iface->condition = USB_INTERFACE_BOUND;
 
+	/* Disable LPM until this driver is bound. */
+	lpm_disable_error = usb_unlocked_disable_lpm(udev);
+	if (lpm_disable_error && driver->disable_hub_initiated_lpm) {
+		dev_err(&iface->dev, "%s Failed to disable LPM for driver %s\n.",
+				__func__, driver->name);
+		return -ENOMEM;
+	}
+
 	/* Claimed interfaces are initially inactive (suspended) and
 	 * runtime-PM-enabled, but only if the driver has autosuspend
 	 * support.  Otherwise they are marked active, to prevent the
@@ -471,6 +519,10 @@ int usb_driver_claim_interface(struct usb_driver *driver,
 	if (device_is_registered(dev))
 		retval = device_bind_driver(dev);
 
+	/* Attempt to re-enable USB3 LPM, if the disable was successful. */
+	if (!lpm_disable_error)
+		usb_unlocked_enable_lpm(udev);
+
 	return retval;
 }
 EXPORT_SYMBOL_GPL(usb_driver_claim_interface);
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 0cd2daacacbe..190b1ec7bdcb 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -997,6 +997,15 @@ static int register_root_hub(struct usb_hcd *hcd)
 				dev_name(&usb_dev->dev), retval);
 		return (retval < 0) ? retval : -EMSGSIZE;
 	}
+	if (usb_dev->speed == USB_SPEED_SUPER) {
+		retval = usb_get_bos_descriptor(usb_dev);
+		if (retval < 0) {
+			mutex_unlock(&usb_bus_list_lock);
+			dev_dbg(parent_dev, "can't read %s bos descriptor %d\n",
+					dev_name(&usb_dev->dev), retval);
+			return retval;
+		}
+	}
 
 	retval = usb_new_device (usb_dev);
 	if (retval) {
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index ec6c97dadbe4..fcc244e9056f 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -177,6 +177,228 @@ static struct usb_hub *hdev_to_hub(struct usb_device *hdev)
 	return usb_get_intfdata(hdev->actconfig->interface[0]);
 }
 
+static int usb_device_supports_lpm(struct usb_device *udev)
+{
+	/* USB 2.1 (and greater) devices indicate LPM support through
+	 * their USB 2.0 Extended Capabilities BOS descriptor.
+	 */
+	if (udev->speed == USB_SPEED_HIGH) {
+		if (udev->bos->ext_cap &&
+			(USB_LPM_SUPPORT &
+			 le32_to_cpu(udev->bos->ext_cap->bmAttributes)))
+			return 1;
+		return 0;
+	}
+
+	/* All USB 3.0 must support LPM, but we need their max exit latency
+	 * information from the SuperSpeed Extended Capabilities BOS descriptor.
+	 */
+	if (!udev->bos->ss_cap) {
+		dev_warn(&udev->dev, "No LPM exit latency info found.  "
+				"Power management will be impacted.\n");
+		return 0;
+	}
+	if (udev->parent->lpm_capable)
+		return 1;
+
+	dev_warn(&udev->dev, "Parent hub missing LPM exit latency info.  "
+			"Power management will be impacted.\n");
+	return 0;
+}
+
+/*
+ * Set the Maximum Exit Latency (MEL) for the host to initiate a transition from
+ * either U1 or U2.
+ */
+static void usb_set_lpm_mel(struct usb_device *udev,
+		struct usb3_lpm_parameters *udev_lpm_params,
+		unsigned int udev_exit_latency,
+		struct usb_hub *hub,
+		struct usb3_lpm_parameters *hub_lpm_params,
+		unsigned int hub_exit_latency)
+{
+	unsigned int total_mel;
+	unsigned int device_mel;
+	unsigned int hub_mel;
+
+	/*
+	 * Calculate the time it takes to transition all links from the roothub
+	 * to the parent hub into U0.  The parent hub must then decode the
+	 * packet (hub header decode latency) to figure out which port it was
+	 * bound for.
+	 *
+	 * The Hub Header decode latency is expressed in 0.1us intervals (0x1
+	 * means 0.1us).  Multiply that by 100 to get nanoseconds.
+	 */
+	total_mel = hub_lpm_params->mel +
+		(hub->descriptor->u.ss.bHubHdrDecLat * 100);
+
+	/*
+	 * How long will it take to transition the downstream hub's port into
+	 * U0?  The greater of either the hub exit latency or the device exit
+	 * latency.
+	 *
+	 * The BOS U1/U2 exit latencies are expressed in 1us intervals.
+	 * Multiply that by 1000 to get nanoseconds.
+	 */
+	device_mel = udev_exit_latency * 1000;
+	hub_mel = hub_exit_latency * 1000;
+	if (device_mel > hub_mel)
+		total_mel += device_mel;
+	else
+		total_mel += hub_mel;
+
+	udev_lpm_params->mel = total_mel;
+}
+
+/*
+ * Set the maximum Device to Host Exit Latency (PEL) for the device to initiate
+ * a transition from either U1 or U2.
+ */
+static void usb_set_lpm_pel(struct usb_device *udev,
+		struct usb3_lpm_parameters *udev_lpm_params,
+		unsigned int udev_exit_latency,
+		struct usb_hub *hub,
+		struct usb3_lpm_parameters *hub_lpm_params,
+		unsigned int hub_exit_latency,
+		unsigned int port_to_port_exit_latency)
+{
+	unsigned int first_link_pel;
+	unsigned int hub_pel;
+
+	/*
+	 * First, the device sends an LFPS to transition the link between the
+	 * device and the parent hub into U0.  The exit latency is the bigger of
+	 * the device exit latency or the hub exit latency.
+	 */
+	if (udev_exit_latency > hub_exit_latency)
+		first_link_pel = udev_exit_latency * 1000;
+	else
+		first_link_pel = hub_exit_latency * 1000;
+
+	/*
+	 * When the hub starts to receive the LFPS, there is a slight delay for
+	 * it to figure out that one of the ports is sending an LFPS.  Then it
+	 * will forward the LFPS to its upstream link.  The exit latency is the
+	 * delay, plus the PEL that we calculated for this hub.
+	 */
+	hub_pel = port_to_port_exit_latency * 1000 + hub_lpm_params->pel;
+
+	/*
+	 * According to figure C-7 in the USB 3.0 spec, the PEL for this device
+	 * is the greater of the two exit latencies.
+	 */
+	if (first_link_pel > hub_pel)
+		udev_lpm_params->pel = first_link_pel;
+	else
+		udev_lpm_params->pel = hub_pel;
+}
+
+/*
+ * Set the System Exit Latency (SEL) to indicate the total worst-case time from
+ * when a device initiates a transition to U0, until when it will receive the
+ * first packet from the host controller.
+ *
+ * Section C.1.5.1 describes the four components to this:
+ *  - t1: device PEL
+ *  - t2: time for the ERDY to make it from the device to the host.
+ *  - t3: a host-specific delay to process the ERDY.
+ *  - t4: time for the packet to make it from the host to the device.
+ *
+ * t3 is specific to both the xHCI host and the platform the host is integrated
+ * into.  The Intel HW folks have said it's negligible, FIXME if a different
+ * vendor says otherwise.
+ */
+static void usb_set_lpm_sel(struct usb_device *udev,
+		struct usb3_lpm_parameters *udev_lpm_params)
+{
+	struct usb_device *parent;
+	unsigned int num_hubs;
+	unsigned int total_sel;
+
+	/* t1 = device PEL */
+	total_sel = udev_lpm_params->pel;
+	/* How many external hubs are in between the device & the root port. */
+	for (parent = udev->parent, num_hubs = 0; parent->parent;
+			parent = parent->parent)
+		num_hubs++;
+	/* t2 = 2.1us + 250ns * (num_hubs - 1) */
+	if (num_hubs > 0)
+		total_sel += 2100 + 250 * (num_hubs - 1);
+
+	/* t4 = 250ns * num_hubs */
+	total_sel += 250 * num_hubs;
+
+	udev_lpm_params->sel = total_sel;
+}
+
+static void usb_set_lpm_parameters(struct usb_device *udev)
+{
+	struct usb_hub *hub;
+	unsigned int port_to_port_delay;
+	unsigned int udev_u1_del;
+	unsigned int udev_u2_del;
+	unsigned int hub_u1_del;
+	unsigned int hub_u2_del;
+
+	if (!udev->lpm_capable || udev->speed != USB_SPEED_SUPER)
+		return;
+
+	hub = hdev_to_hub(udev->parent);
+	/* It doesn't take time to transition the roothub into U0, since it
+	 * doesn't have an upstream link.
+	 */
+	if (!hub)
+		return;
+
+	udev_u1_del = udev->bos->ss_cap->bU1devExitLat;
+	udev_u2_del = udev->bos->ss_cap->bU2DevExitLat;
+	hub_u1_del = udev->parent->bos->ss_cap->bU1devExitLat;
+	hub_u2_del = udev->parent->bos->ss_cap->bU2DevExitLat;
+
+	usb_set_lpm_mel(udev, &udev->u1_params, udev_u1_del,
+			hub, &udev->parent->u1_params, hub_u1_del);
+
+	usb_set_lpm_mel(udev, &udev->u2_params, udev_u2_del,
+			hub, &udev->parent->u2_params, hub_u2_del);
+
+	/*
+	 * Appendix C, section C.2.2.2, says that there is a slight delay from
+	 * when the parent hub notices the downstream port is trying to
+	 * transition to U0 to when the hub initiates a U0 transition on its
+	 * upstream port.  The section says the delays are tPort2PortU1EL and
+	 * tPort2PortU2EL, but it doesn't define what they are.
+	 *
+	 * The hub chapter, sections 10.4.2.4 and 10.4.2.5 seem to be talking
+	 * about the same delays.  Use the maximum delay calculations from those
+	 * sections.  For U1, it's tHubPort2PortExitLat, which is 1us max.  For
+	 * U2, it's tHubPort2PortExitLat + U2DevExitLat - U1DevExitLat.  I
+	 * assume the device exit latencies they are talking about are the hub
+	 * exit latencies.
+	 *
+	 * What do we do if the U2 exit latency is less than the U1 exit
+	 * latency?  It's possible, although not likely...
+	 */
+	port_to_port_delay = 1;
+
+	usb_set_lpm_pel(udev, &udev->u1_params, udev_u1_del,
+			hub, &udev->parent->u1_params, hub_u1_del,
+			port_to_port_delay);
+
+	if (hub_u2_del > hub_u1_del)
+		port_to_port_delay = 1 + hub_u2_del - hub_u1_del;
+	else
+		port_to_port_delay = 1 + hub_u1_del;
+
+	usb_set_lpm_pel(udev, &udev->u2_params, udev_u2_del,
+			hub, &udev->parent->u2_params, hub_u2_del,
+			port_to_port_delay);
+
+	/* Now that we've got PEL, calculate SEL. */
+	usb_set_lpm_sel(udev, &udev->u1_params);
+	usb_set_lpm_sel(udev, &udev->u2_params);
+}
+
 /* USB 2.0 spec Section 11.24.4.5 */
 static int get_hub_descriptor(struct usb_device *hdev, void *data)
 {
@@ -2480,6 +2702,12 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
 	if (udev->usb2_hw_lpm_enabled == 1)
 		usb_set_usb2_hardware_lpm(udev, 0);
 
+	if (usb_unlocked_disable_lpm(udev)) {
+		dev_err(&udev->dev, "%s Failed to disable LPM before suspend\n.",
+				__func__);
+		return -ENOMEM;
+	}
+
 	/* see 7.1.7.6 */
 	if (hub_is_superspeed(hub->hdev))
 		status = set_port_feature(hub->hdev,
@@ -2499,6 +2727,13 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
 				NULL, 0,
 				USB_CTRL_SET_TIMEOUT);
 
+		/* Try to enable USB2 hardware LPM again */
+		if (udev->usb2_hw_lpm_capable == 1)
+			usb_set_usb2_hardware_lpm(udev, 1);
+
+		/* Try to enable USB3 LPM again */
+		usb_unlocked_enable_lpm(udev);
+
 		/* System sleep transitions should never fail */
 		if (!PMSG_IS_AUTO(msg))
 			status = 0;
@@ -2696,6 +2931,9 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
 		/* Try to enable USB2 hardware LPM */
 		if (udev->usb2_hw_lpm_capable == 1)
 			usb_set_usb2_hardware_lpm(udev, 1);
+
+		/* Try to enable USB3 LPM */
+		usb_unlocked_enable_lpm(udev);
 	}
 
 	return status;
@@ -2824,11 +3062,425 @@ void usb_root_hub_lost_power(struct usb_device *rhdev)
 }
 EXPORT_SYMBOL_GPL(usb_root_hub_lost_power);
 
+static const char * const usb3_lpm_names[]  = {
+	"U0",
+	"U1",
+	"U2",
+	"U3",
+};
+
+/*
+ * Send a Set SEL control transfer to the device, prior to enabling
+ * device-initiated U1 or U2.  This lets the device know the exit latencies from
+ * the time the device initiates a U1 or U2 exit, to the time it will receive a
+ * packet from the host.
+ *
+ * This function will fail if the SEL or PEL values for udev are greater than
+ * the maximum allowed values for the link state to be enabled.
+ */
+static int usb_req_set_sel(struct usb_device *udev, enum usb3_link_state state)
+{
+	struct usb_set_sel_req *sel_values;
+	unsigned long long u1_sel;
+	unsigned long long u1_pel;
+	unsigned long long u2_sel;
+	unsigned long long u2_pel;
+	int ret;
+
+	/* Convert SEL and PEL stored in ns to us */
+	u1_sel = DIV_ROUND_UP(udev->u1_params.sel, 1000);
+	u1_pel = DIV_ROUND_UP(udev->u1_params.pel, 1000);
+	u2_sel = DIV_ROUND_UP(udev->u2_params.sel, 1000);
+	u2_pel = DIV_ROUND_UP(udev->u2_params.pel, 1000);
+
+	/*
+	 * Make sure that the calculated SEL and PEL values for the link
+	 * state we're enabling aren't bigger than the max SEL/PEL
+	 * value that will fit in the SET SEL control transfer.
+	 * Otherwise the device would get an incorrect idea of the exit
+	 * latency for the link state, and could start a device-initiated
+	 * U1/U2 when the exit latencies are too high.
+	 */
+	if ((state == USB3_LPM_U1 &&
+				(u1_sel > USB3_LPM_MAX_U1_SEL_PEL ||
+				 u1_pel > USB3_LPM_MAX_U1_SEL_PEL)) ||
+			(state == USB3_LPM_U2 &&
+			 (u2_sel > USB3_LPM_MAX_U2_SEL_PEL ||
+			  u2_pel > USB3_LPM_MAX_U2_SEL_PEL))) {
+		dev_dbg(&udev->dev, "Device-initiated %s disabled due "
+				"to long SEL %llu ms or PEL %llu ms\n",
+				usb3_lpm_names[state], u1_sel, u1_pel);
+		return -EINVAL;
+	}
+
+	/*
+	 * If we're enabling device-initiated LPM for one link state,
+	 * but the other link state has a too high SEL or PEL value,
+	 * just set those values to the max in the Set SEL request.
+	 */
+	if (u1_sel > USB3_LPM_MAX_U1_SEL_PEL)
+		u1_sel = USB3_LPM_MAX_U1_SEL_PEL;
+
+	if (u1_pel > USB3_LPM_MAX_U1_SEL_PEL)
+		u1_pel = USB3_LPM_MAX_U1_SEL_PEL;
+
+	if (u2_sel > USB3_LPM_MAX_U2_SEL_PEL)
+		u2_sel = USB3_LPM_MAX_U2_SEL_PEL;
+
+	if (u2_pel > USB3_LPM_MAX_U2_SEL_PEL)
+		u2_pel = USB3_LPM_MAX_U2_SEL_PEL;
+
+	/*
+	 * usb_enable_lpm() can be called as part of a failed device reset,
+	 * which may be initiated by an error path of a mass storage driver.
+	 * Therefore, use GFP_NOIO.
+	 */
+	sel_values = kmalloc(sizeof *(sel_values), GFP_NOIO);
+	if (!sel_values)
+		return -ENOMEM;
+
+	sel_values->u1_sel = u1_sel;
+	sel_values->u1_pel = u1_pel;
+	sel_values->u2_sel = cpu_to_le16(u2_sel);
+	sel_values->u2_pel = cpu_to_le16(u2_pel);
+
+	ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
+			USB_REQ_SET_SEL,
+			USB_RECIP_DEVICE,
+			0, 0,
+			sel_values, sizeof *(sel_values),
+			USB_CTRL_SET_TIMEOUT);
+	kfree(sel_values);
+	return ret;
+}
+
+/*
+ * Enable or disable device-initiated U1 or U2 transitions.
+ */
+static int usb_set_device_initiated_lpm(struct usb_device *udev,
+		enum usb3_link_state state, bool enable)
+{
+	int ret;
+	int feature;
+
+	switch (state) {
+	case USB3_LPM_U1:
+		feature = USB_DEVICE_U1_ENABLE;
+		break;
+	case USB3_LPM_U2:
+		feature = USB_DEVICE_U2_ENABLE;
+		break;
+	default:
+		dev_warn(&udev->dev, "%s: Can't %s non-U1 or U2 state.\n",
+				__func__, enable ? "enable" : "disable");
+		return -EINVAL;
+	}
+
+	if (udev->state != USB_STATE_CONFIGURED) {
+		dev_dbg(&udev->dev, "%s: Can't %s %s state "
+				"for unconfigured device.\n",
+				__func__, enable ? "enable" : "disable",
+				usb3_lpm_names[state]);
+		return 0;
+	}
+
+	if (enable) {
+		/*
+		 * First, let the device know about the exit latencies
+		 * associated with the link state we're about to enable.
+		 */
+		ret = usb_req_set_sel(udev, state);
+		if (ret < 0) {
+			dev_warn(&udev->dev, "Set SEL for device-initiated "
+					"%s failed.\n", usb3_lpm_names[state]);
+			return -EBUSY;
+		}
+		/*
+		 * Now send the control transfer to enable device-initiated LPM
+		 * for either U1 or U2.
+		 */
+		ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
+				USB_REQ_SET_FEATURE,
+				USB_RECIP_DEVICE,
+				feature,
+				0, NULL, 0,
+				USB_CTRL_SET_TIMEOUT);
+	} else {
+		ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
+				USB_REQ_CLEAR_FEATURE,
+				USB_RECIP_DEVICE,
+				feature,
+				0, NULL, 0,
+				USB_CTRL_SET_TIMEOUT);
+	}
+	if (ret < 0) {
+		dev_warn(&udev->dev, "%s of device-initiated %s failed.\n",
+				enable ? "Enable" : "Disable",
+				usb3_lpm_names[state]);
+		return -EBUSY;
+	}
+	return 0;
+}
+
+static int usb_set_lpm_timeout(struct usb_device *udev,
+		enum usb3_link_state state, int timeout)
+{
+	int ret;
+	int feature;
+
+	switch (state) {
+	case USB3_LPM_U1:
+		feature = USB_PORT_FEAT_U1_TIMEOUT;
+		break;
+	case USB3_LPM_U2:
+		feature = USB_PORT_FEAT_U2_TIMEOUT;
+		break;
+	default:
+		dev_warn(&udev->dev, "%s: Can't set timeout for non-U1 or U2 state.\n",
+				__func__);
+		return -EINVAL;
+	}
+
+	if (state == USB3_LPM_U1 && timeout > USB3_LPM_U1_MAX_TIMEOUT &&
+			timeout != USB3_LPM_DEVICE_INITIATED) {
+		dev_warn(&udev->dev, "Failed to set %s timeout to 0x%x, "
+				"which is a reserved value.\n",
+				usb3_lpm_names[state], timeout);
+		return -EINVAL;
+	}
+
+	ret = set_port_feature(udev->parent,
+			USB_PORT_LPM_TIMEOUT(timeout) | udev->portnum,
+			feature);
+	if (ret < 0) {
+		dev_warn(&udev->dev, "Failed to set %s timeout to 0x%x,"
+				"error code %i\n", usb3_lpm_names[state],
+				timeout, ret);
+		return -EBUSY;
+	}
+	if (state == USB3_LPM_U1)
+		udev->u1_params.timeout = timeout;
+	else
+		udev->u2_params.timeout = timeout;
+	return 0;
+}
+
+/*
+ * Enable the hub-initiated U1/U2 idle timeouts, and enable device-initiated
+ * U1/U2 entry.
+ *
+ * We will attempt to enable U1 or U2, but there are no guarantees that the
+ * control transfers to set the hub timeout or enable device-initiated U1/U2
+ * will be successful.
+ *
+ * If we cannot set the parent hub U1/U2 timeout, we attempt to let the xHCI
+ * driver know about it.  If that call fails, it should be harmless, and just
+ * take up more slightly more bus bandwidth for unnecessary U1/U2 exit latency.
+ */
+static void usb_enable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
+		enum usb3_link_state state)
+{
+	int timeout;
+
+	/* We allow the host controller to set the U1/U2 timeout internally
+	 * first, so that it can change its schedule to account for the
+	 * additional latency to send data to a device in a lower power
+	 * link state.
+	 */
+	timeout = hcd->driver->enable_usb3_lpm_timeout(hcd, udev, state);
+
+	/* xHCI host controller doesn't want to enable this LPM state. */
+	if (timeout == 0)
+		return;
+
+	if (timeout < 0) {
+		dev_warn(&udev->dev, "Could not enable %s link state, "
+				"xHCI error %i.\n", usb3_lpm_names[state],
+				timeout);
+		return;
+	}
+
+	if (usb_set_lpm_timeout(udev, state, timeout))
+		/* If we can't set the parent hub U1/U2 timeout,
+		 * device-initiated LPM won't be allowed either, so let the xHCI
+		 * host know that this link state won't be enabled.
+		 */
+		hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);
+
+	/* Only a configured device will accept the Set Feature U1/U2_ENABLE */
+	else if (udev->actconfig)
+		usb_set_device_initiated_lpm(udev, state, true);
+
+}
+
+/*
+ * Disable the hub-initiated U1/U2 idle timeouts, and disable device-initiated
+ * U1/U2 entry.
+ *
+ * If this function returns -EBUSY, the parent hub will still allow U1/U2 entry.
+ * If zero is returned, the parent will not allow the link to go into U1/U2.
+ *
+ * If zero is returned, device-initiated U1/U2 entry may still be enabled, but
+ * it won't have an effect on the bus link state because the parent hub will
+ * still disallow device-initiated U1/U2 entry.
+ *
+ * If zero is returned, the xHCI host controller may still think U1/U2 entry is
+ * possible.  The result will be slightly more bus bandwidth will be taken up
+ * (to account for U1/U2 exit latency), but it should be harmless.
+ */
+static int usb_disable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
+		enum usb3_link_state state)
+{
+	int feature;
+
+	switch (state) {
+	case USB3_LPM_U1:
+		feature = USB_PORT_FEAT_U1_TIMEOUT;
+		break;
+	case USB3_LPM_U2:
+		feature = USB_PORT_FEAT_U2_TIMEOUT;
+		break;
+	default:
+		dev_warn(&udev->dev, "%s: Can't disable non-U1 or U2 state.\n",
+				__func__);
+		return -EINVAL;
+	}
+
+	if (usb_set_lpm_timeout(udev, state, 0))
+		return -EBUSY;
+
+	usb_set_device_initiated_lpm(udev, state, false);
+
+	if (hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state))
+		dev_warn(&udev->dev, "Could not disable xHCI %s timeout, "
+				"bus schedule bandwidth may be impacted.\n",
+				usb3_lpm_names[state]);
+	return 0;
+}
+
+/*
+ * Disable hub-initiated and device-initiated U1 and U2 entry.
+ * Caller must own the bandwidth_mutex.
+ *
+ * This will call usb_enable_lpm() on failure, which will decrement
+ * lpm_disable_count, and will re-enable LPM if lpm_disable_count reaches zero.
+ */
+int usb_disable_lpm(struct usb_device *udev)
+{
+	struct usb_hcd *hcd;
+
+	if (!udev || !udev->parent ||
+			udev->speed != USB_SPEED_SUPER ||
+			!udev->lpm_capable)
+		return 0;
+
+	hcd = bus_to_hcd(udev->bus);
+	if (!hcd || !hcd->driver->disable_usb3_lpm_timeout)
+		return 0;
+
+	udev->lpm_disable_count++;
+	if ((udev->u1_params.timeout == 0 && udev->u1_params.timeout == 0))
+		return 0;
+
+	/* If LPM is enabled, attempt to disable it. */
+	if (usb_disable_link_state(hcd, udev, USB3_LPM_U1))
+		goto enable_lpm;
+	if (usb_disable_link_state(hcd, udev, USB3_LPM_U2))
+		goto enable_lpm;
+
+	return 0;
+
+enable_lpm:
+	usb_enable_lpm(udev);
+	return -EBUSY;
+}
+EXPORT_SYMBOL_GPL(usb_disable_lpm);
+
+/* Grab the bandwidth_mutex before calling usb_disable_lpm() */
+int usb_unlocked_disable_lpm(struct usb_device *udev)
+{
+	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
+	int ret;
+
+	if (!hcd)
+		return -EINVAL;
+
+	mutex_lock(hcd->bandwidth_mutex);
+	ret = usb_disable_lpm(udev);
+	mutex_unlock(hcd->bandwidth_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm);
+
+/*
+ * Attempt to enable device-initiated and hub-initiated U1 and U2 entry.  The
+ * xHCI host policy may prevent U1 or U2 from being enabled.
+ *
+ * Other callers may have disabled link PM, so U1 and U2 entry will be disabled
+ * until the lpm_disable_count drops to zero.  Caller must own the
+ * bandwidth_mutex.
+ */
+void usb_enable_lpm(struct usb_device *udev)
+{
+	struct usb_hcd *hcd;
+
+	if (!udev || !udev->parent ||
+			udev->speed != USB_SPEED_SUPER ||
+			!udev->lpm_capable)
+		return;
+
+	udev->lpm_disable_count--;
+	hcd = bus_to_hcd(udev->bus);
+	/* Double check that we can both enable and disable LPM.
+	 * Device must be configured to accept set feature U1/U2 timeout.
+	 */
+	if (!hcd || !hcd->driver->enable_usb3_lpm_timeout ||
+			!hcd->driver->disable_usb3_lpm_timeout)
+		return;
+
+	if (udev->lpm_disable_count > 0)
+		return;
+
+	usb_enable_link_state(hcd, udev, USB3_LPM_U1);
+	usb_enable_link_state(hcd, udev, USB3_LPM_U2);
+}
+EXPORT_SYMBOL_GPL(usb_enable_lpm);
+
+/* Grab the bandwidth_mutex before calling usb_enable_lpm() */
+void usb_unlocked_enable_lpm(struct usb_device *udev)
+{
+	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
+
+	if (!hcd)
+		return;
+
+	mutex_lock(hcd->bandwidth_mutex);
+	usb_enable_lpm(udev);
+	mutex_unlock(hcd->bandwidth_mutex);
+}
+EXPORT_SYMBOL_GPL(usb_unlocked_enable_lpm);
+
+
 #else	/* CONFIG_PM */
 
 #define hub_suspend		NULL
 #define hub_resume		NULL
 #define hub_reset_resume	NULL
+
+int usb_disable_lpm(struct usb_device *udev)
+{
+	return 0;
+}
+
+void usb_enable_lpm(struct usb_device *udev) { }
+
+int usb_unlocked_disable_lpm(struct usb_device *udev)
+{
+	return 0;
+}
+
+void usb_unlocked_enable_lpm(struct usb_device *udev) { }
 #endif
 
 
@@ -3208,9 +3860,8 @@ hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
 	if (udev->wusb == 0 && le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0201) {
 		retval = usb_get_bos_descriptor(udev);
 		if (!retval) {
-			if (udev->bos->ext_cap && (USB_LPM_SUPPORT &
-				le32_to_cpu(udev->bos->ext_cap->bmAttributes)))
-					udev->lpm_capable = 1;
+			udev->lpm_capable = usb_device_supports_lpm(udev);
+			usb_set_lpm_parameters(udev);
 		}
 	}
 
@@ -4042,11 +4693,22 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 		goto done;
 
 	mutex_lock(hcd->bandwidth_mutex);
+	/* Disable LPM while we reset the device and reinstall the alt settings.
+	 * Device-initiated LPM settings, and system exit latency settings are
+	 * cleared when the device is reset, so we have to set them up again.
+	 */
+	ret = usb_disable_lpm(udev);
+	if (ret) {
+		dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__);
+		mutex_unlock(hcd->bandwidth_mutex);
+		goto done;
+	}
 	ret = usb_hcd_alloc_bandwidth(udev, udev->actconfig, NULL, NULL);
 	if (ret < 0) {
 		dev_warn(&udev->dev,
 				"Busted HC?  Not enough HCD resources for "
 				"old configuration.\n");
+		usb_enable_lpm(udev);
 		mutex_unlock(hcd->bandwidth_mutex);
 		goto re_enumerate;
 	}
@@ -4058,6 +4720,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 		dev_err(&udev->dev,
 			"can't restore configuration #%d (error=%d)\n",
 			udev->actconfig->desc.bConfigurationValue, ret);
+		usb_enable_lpm(udev);
 		mutex_unlock(hcd->bandwidth_mutex);
 		goto re_enumerate;
   	}
@@ -4096,10 +4759,13 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
 				desc->bInterfaceNumber,
 				desc->bAlternateSetting,
 				ret);
+			usb_unlocked_enable_lpm(udev);
 			goto re_enumerate;
 		}
 	}
 
+	/* Now that the alt settings are re-installed, enable LPM. */
+	usb_unlocked_enable_lpm(udev);
 done:
 	return 0;
  
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index ca717da3be95..b548cf1dbc62 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1308,10 +1308,19 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
 	 * Remove the current alt setting and add the new alt setting.
 	 */
 	mutex_lock(hcd->bandwidth_mutex);
+	/* Disable LPM, and re-enable it once the new alt setting is installed,
+	 * so that the xHCI driver can recalculate the U1/U2 timeouts.
+	 */
+	if (usb_disable_lpm(dev)) {
+		dev_err(&iface->dev, "%s Failed to disable LPM\n.", __func__);
+		mutex_unlock(hcd->bandwidth_mutex);
+		return -ENOMEM;
+	}
 	ret = usb_hcd_alloc_bandwidth(dev, NULL, iface->cur_altsetting, alt);
 	if (ret < 0) {
 		dev_info(&dev->dev, "Not enough bandwidth for altsetting %d\n",
 				alternate);
+		usb_enable_lpm(dev);
 		mutex_unlock(hcd->bandwidth_mutex);
 		return ret;
 	}
@@ -1334,6 +1343,7 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
 	} else if (ret < 0) {
 		/* Re-instate the old alt setting */
 		usb_hcd_alloc_bandwidth(dev, NULL, alt, iface->cur_altsetting);
+		usb_enable_lpm(dev);
 		mutex_unlock(hcd->bandwidth_mutex);
 		return ret;
 	}
@@ -1354,6 +1364,9 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
 
 	iface->cur_altsetting = alt;
 
+	/* Now that the interface is installed, re-enable LPM. */
+	usb_unlocked_enable_lpm(dev);
+
 	/* If the interface only has one altsetting and the device didn't
 	 * accept the request, we attempt to carry out the equivalent action
 	 * by manually clearing the HALT feature for each endpoint in the
@@ -1437,6 +1450,14 @@ int usb_reset_configuration(struct usb_device *dev)
 	config = dev->actconfig;
 	retval = 0;
 	mutex_lock(hcd->bandwidth_mutex);
+	/* Disable LPM, and re-enable it once the configuration is reset, so
+	 * that the xHCI driver can recalculate the U1/U2 timeouts.
+	 */
+	if (usb_disable_lpm(dev)) {
+		dev_err(&dev->dev, "%s Failed to disable LPM\n.", __func__);
+		mutex_unlock(hcd->bandwidth_mutex);
+		return -ENOMEM;
+	}
 	/* Make sure we have enough bandwidth for each alternate setting 0 */
 	for (i =