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

6 files changed, 558 insertions, 7 deletions

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 89850a82d51b..2732ef660c5c 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -475,6 +475,7 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 	struct xhci_bus_state *bus_state;
 	u16 link_state = 0;
 	u16 wake_mask = 0;
+	u16 timeout = 0;
 
 	max_ports = xhci_get_ports(hcd, &port_array);
 	bus_state = &xhci->bus_state[hcd_index(hcd)];
@@ -623,6 +624,8 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 			link_state = (wIndex & 0xff00) >> 3;
 		if (wValue == USB_PORT_FEAT_REMOTE_WAKE_MASK)
 			wake_mask = wIndex & 0xff00;
+		/* The MSB of wIndex is the U1/U2 timeout */
+		timeout = (wIndex & 0xff00) >> 8;
 		wIndex &= 0xff;
 		if (!wIndex || wIndex > max_ports)
 			goto error;
@@ -747,6 +750,22 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 
 			temp = xhci_readl(xhci, port_array[wIndex]);
 			break;
+		case USB_PORT_FEAT_U1_TIMEOUT:
+			if (hcd->speed != HCD_USB3)
+				goto error;
+			temp = xhci_readl(xhci, port_array[wIndex] + 1);
+			temp &= ~PORT_U1_TIMEOUT_MASK;
+			temp |= PORT_U1_TIMEOUT(timeout);
+			xhci_writel(xhci, temp, port_array[wIndex] + 1);
+			break;
+		case USB_PORT_FEAT_U2_TIMEOUT:
+			if (hcd->speed != HCD_USB3)
+				goto error;
+			temp = xhci_readl(xhci, port_array[wIndex] + 1);
+			temp &= ~PORT_U2_TIMEOUT_MASK;
+			temp |= PORT_U2_TIMEOUT(timeout);
+			xhci_writel(xhci, temp, port_array[wIndex] + 1);
+			break;
 		default:
 			goto error;
 		}
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 68eaa908ac8e..ec4338eec826 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1791,6 +1791,14 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 {
 	struct pci_dev	*pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);
 	struct dev_info	*dev_info, *next;
+	struct list_head *tt_list_head;
+	struct list_head *tt;
+	struct list_head *endpoints;
+	struct list_head *ep, *q;
+	struct xhci_tt_bw_info *tt_info;
+	struct xhci_interval_bw_table *bwt;
+	struct xhci_virt_ep *virt_ep;
+
 	unsigned long	flags;
 	int size;
 	int i;
@@ -1807,6 +1815,9 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 	xhci->event_ring = NULL;
 	xhci_dbg(xhci, "Freed event ring\n");
 
+	if (xhci->lpm_command)
+		xhci_free_command(xhci, xhci->lpm_command);
+	xhci->cmd_ring_reserved_trbs = 0;
 	if (xhci->cmd_ring)
 		xhci_ring_free(xhci, xhci->cmd_ring);
 	xhci->cmd_ring = NULL;
@@ -1849,8 +1860,26 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 	}
 	spin_unlock_irqrestore(&xhci->lock, flags);
 
+	bwt = &xhci->rh_bw->bw_table;
+	for (i = 0; i < XHCI_MAX_INTERVAL; i++) {
+		endpoints = &bwt->interval_bw[i].endpoints;
+		list_for_each_safe(ep, q, endpoints) {
+			virt_ep = list_entry(ep, struct xhci_virt_ep, bw_endpoint_list);
+			list_del(&virt_ep->bw_endpoint_list);
+			kfree(virt_ep);
+		}
+	}
+
+	tt_list_head = &xhci->rh_bw->tts;
+	list_for_each_safe(tt, q, tt_list_head) {
+		tt_info = list_entry(tt, struct xhci_tt_bw_info, tt_list);
+		list_del(tt);
+		kfree(tt_info);
+	}
+
 	xhci->num_usb2_ports = 0;
 	xhci->num_usb3_ports = 0;
+	xhci->num_active_eps = 0;
 	kfree(xhci->usb2_ports);
 	kfree(xhci->usb3_ports);
 	kfree(xhci->port_array);
@@ -2350,6 +2379,16 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 	xhci_write_64(xhci, val_64, &xhci->op_regs->cmd_ring);
 	xhci_dbg_cmd_ptrs(xhci);
 
+	xhci->lpm_command = xhci_alloc_command(xhci, true, true, flags);
+	if (!xhci->lpm_command)
+		goto fail;
+
+	/* Reserve one command ring TRB for disabling LPM.
+	 * Since the USB core grabs the shared usb_bus bandwidth mutex before
+	 * disabling LPM, we only need to reserve one TRB for all devices.
+	 */
+	xhci->cmd_ring_reserved_trbs++;
+
 	val = xhci_readl(xhci, &xhci->cap_regs->db_off);
 	val &= DBOFF_MASK;
 	xhci_dbg(xhci, "// Doorbell array is located at offset 0x%x"
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 7a856a767e77..18b231b0c5d3 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -72,6 +72,7 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 		xhci_dbg(xhci, "QUIRK: Fresco Logic revision %u "
 				"has broken MSI implementation\n",
 				pdev->revision);
+		xhci->quirks |= XHCI_TRUST_TX_LENGTH;
 	}
 
 	if (pdev->vendor == PCI_VENDOR_ID_NEC)
@@ -83,6 +84,10 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 	/* AMD PLL quirk */
 	if (pdev->vendor == PCI_VENDOR_ID_AMD && usb_amd_find_chipset_info())
 		xhci->quirks |= XHCI_AMD_PLL_FIX;
+	if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
+		xhci->quirks |= XHCI_LPM_SUPPORT;
+		xhci->quirks |= XHCI_INTEL_HOST;
+	}
 	if (pdev->vendor == PCI_VENDOR_ID_INTEL &&
 			pdev->device == PCI_DEVICE_ID_INTEL_PANTHERPOINT_XHCI) {
 		xhci->quirks |= XHCI_SPURIOUS_SUCCESS;
@@ -169,6 +174,13 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (retval)
 		goto put_usb3_hcd;
 	/* Roothub already marked as USB 3.0 speed */
+
+	/* We know the LPM timeout algorithms for this host, let the USB core
+	 * enable and disable LPM for devices under the USB 3.0 roothub.
+	 */
+	if (xhci->quirks & XHCI_LPM_SUPPORT)
+		hcd_to_bus(xhci->shared_hcd)->root_hub->lpm_capable = 1;
+
 	return 0;
 
 put_usb3_hcd:
@@ -292,6 +304,8 @@ static const struct hc_driver xhci_pci_hc_driver = {
 	 */
 	.update_device =        xhci_update_device,
 	.set_usb2_hw_lpm =	xhci_set_usb2_hardware_lpm,
+	.enable_usb3_lpm_timeout =	xhci_enable_usb3_lpm_timeout,
+	.disable_usb3_lpm_timeout =	xhci_disable_usb3_lpm_timeout,
 };
 
 /*-------------------------------------------------------------------------*/
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 329fd2a98dd6..23b4aefd1036 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1787,8 +1787,12 @@ static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,
 	/* handle completion code */
 	switch (trb_comp_code) {
 	case COMP_SUCCESS:
-		frame->status = 0;
-		break;
+		if (TRB_LEN(le32_to_cpu(event->transfer_len)) == 0) {
+			frame->status = 0;
+			break;
+		}
+		if ((xhci->quirks & XHCI_TRUST_TX_LENGTH))
+			trb_comp_code = COMP_SHORT_TX;
 	case COMP_SHORT_TX:
 		frame->status = td->urb->transfer_flags & URB_SHORT_NOT_OK ?
 				-EREMOTEIO : 0;
@@ -1885,13 +1889,16 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 	switch (trb_comp_code) {
 	case COMP_SUCCESS:
 		/* Double check that the HW transferred everything. */
-		if (event_trb != td->last_trb) {
+		if (event_trb != td->last_trb ||
+				TRB_LEN(le32_to_cpu(event->transfer_len)) != 0) {
 			xhci_warn(xhci, "WARN Successful completion "
 					"on short TX\n");
 			if (td->urb->transfer_flags & URB_SHORT_NOT_OK)
 				*status = -EREMOTEIO;
 			else
 				*status = 0;
+			if ((xhci->quirks & XHCI_TRUST_TX_LENGTH))
+				trb_comp_code = COMP_SHORT_TX;
 		} else {
 			*status = 0;
 		}
@@ -2050,6 +2057,13 @@ static int handle_tx_event(struct xhci_hcd *xhci,
 	 * transfer type
 	 */
 	case COMP_SUCCESS:
+		if (TRB_LEN(le32_to_cpu(event->transfer_len)) == 0)
+			break;
+		if (xhci->quirks & XHCI_TRUST_TX_LENGTH)
+			trb_comp_code = COMP_SHORT_TX;
+		else
+			xhci_warn(xhci, "WARN Successful completion on short TX: "
+					"needs XHCI_TRUST_TX_LENGTH quirk?\n");
 	case COMP_SHORT_TX:
 		break;
 	case COMP_STOP:
@@ -3595,12 +3609,12 @@ int xhci_queue_configure_endpoint(struct xhci_hcd *xhci, dma_addr_t in_ctx_ptr,
 
 /* Queue an evaluate context command TRB */
 int xhci_queue_evaluate_context(struct xhci_hcd *xhci, dma_addr_t in_ctx_ptr,
-		u32 slot_id)
+		u32 slot_id, bool command_must_succeed)
 {
 	return queue_command(xhci, lower_32_bits(in_ctx_ptr),
 			upper_32_bits(in_ctx_ptr), 0,
 			TRB_TYPE(TRB_EVAL_CONTEXT) | SLOT_ID_FOR_TRB(slot_id),
-			false);
+			command_must_succeed);
 }
 
 /*
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 16c05c6b5afa..4ceba145fa88 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -2446,7 +2446,7 @@ static int xhci_configure_endpoint(struct xhci_hcd *xhci,
 				udev->slot_id, must_succeed);
 	else
 		ret = xhci_queue_evaluate_context(xhci, in_ctx->dma,
-				udev->slot_id);
+				udev->slot_id, must_succeed);
 	if (ret < 0) {
 		if (command)
 			list_del(&command->cmd_list);
@@ -3837,6 +3837,458 @@ int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
 	return 0;
 }
 
+/*---------------------- USB 3.0 Link PM functions ------------------------*/
+
+/* Service interval in nanoseconds = 2^(bInterval - 1) * 125us * 1000ns / 1us */
+static unsigned long long xhci_service_interval_to_ns(
+		struct usb_endpoint_descriptor *desc)
+{
+	return (1 << (desc->bInterval - 1)) * 125 * 1000;
+}
+
+static u16 xhci_get_timeout_no_hub_lpm(struct usb_device *udev,
+		enum usb3_link_state state)
+{
+	unsigned long long sel;
+	unsigned long long pel;
+	unsigned int max_sel_pel;
+	char *state_name;
+
+	switch (state) {
+	case USB3_LPM_U1:
+		/* Convert SEL and PEL stored in nanoseconds to microseconds */
+		sel = DIV_ROUND_UP(udev->u1_params.sel, 1000);
+		pel = DIV_ROUND_UP(udev->u1_params.pel, 1000);
+		max_sel_pel = USB3_LPM_MAX_U1_SEL_PEL;
+		state_name = "U1";
+		break;
+	case USB3_LPM_U2:
+		sel = DIV_ROUND_UP(udev->u2_params.sel, 1000);
+		pel = DIV_ROUND_UP(udev->u2_params.pel, 1000);
+		max_sel_pel = USB3_LPM_MAX_U2_SEL_PEL;
+		state_name = "U2";
+		break;
+	default:
+		dev_warn(&udev->dev, "%s: Can't get timeout for non-U1 or U2 state.\n",
+				__func__);
+		return -EINVAL;
+	}
+
+	if (sel <= max_sel_pel && pel <= max_sel_pel)
+		return USB3_LPM_DEVICE_INITIATED;
+
+	if (sel > max_sel_pel)
+		dev_dbg(&udev->dev, "Device-initiated %s disabled "
+				"due to long SEL %llu ms\n",
+				state_name, sel);
+	else
+		dev_dbg(&udev->dev, "Device-initiated %s disabled "
+				"due to long PEL %llu\n ms",
+				state_name, pel);
+	return USB3_LPM_DISABLED;
+}
+
+/* Returns the hub-encoded U1 timeout value.
+ * The U1 timeout should be the maximum of the following values:
+ *  - For control endpoints, U1 system exit latency (SEL) * 3
+ *  - For bulk endpoints, U1 SEL * 5
+ *  - For interrupt endpoints:
+ *    - Notification EPs, U1 SEL * 3
+ *    - Periodic EPs, max(105% of bInterval, U1 SEL * 2)
+ *  - For isochronous endpoints, max(105% of bInterval, U1 SEL * 2)
+ */
+static u16 xhci_calculate_intel_u1_timeout(struct usb_device *udev,
+		struct usb_endpoint_descriptor *desc)
+{
+	unsigned long long timeout_ns;
+	int ep_type;
+	int intr_type;
+
+	ep_type = usb_endpoint_type(desc);
+	switch (ep_type) {
+	case USB_ENDPOINT_XFER_CONTROL:
+		timeout_ns = udev->u1_params.sel * 3;
+		break;
+	case USB_ENDPOINT_XFER_BULK:
+		timeout_ns = udev->u1_params.sel * 5;
+		break;
+	case USB_ENDPOINT_XFER_INT:
+		intr_type = usb_endpoint_interrupt_type(desc);
+		if (intr_type == USB_ENDPOINT_INTR_NOTIFICATION) {
+			timeout_ns = udev->u1_params.sel * 3;
+			break;
+		}
+		/* Otherwise the calculation is the same as isoc eps */
+	case USB_ENDPOINT_XFER_ISOC:
+		timeout_ns = xhci_service_interval_to_ns(desc);
+		timeout_ns = DIV_ROUND_UP(timeout_ns * 105, 100);
+		if (timeout_ns < udev->u1_params.sel * 2)
+			timeout_ns = udev->u1_params.sel * 2;
+		break;
+	default:
+		return 0;
+	}
+
+	/* The U1 timeout is encoded in 1us intervals. */
+	timeout_ns = DIV_ROUND_UP(timeout_ns, 1000);
+	/* Don't return a timeout of zero, because that's USB3_LPM_DISABLED. */
+	if (timeout_ns == USB3_LPM_DISABLED)
+		timeout_ns++;
+
+	/* If the necessary timeout value is bigger than what we can set in the
+	 * USB 3.0 hub, we have to disable hub-initiated U1.
+	 */
+	if (timeout_ns <= USB3_LPM_U1_MAX_TIMEOUT)
+		return timeout_ns;
+	dev_dbg(&udev->dev, "Hub-initiated U1 disabled "
+			"due to long timeout %llu ms\n", timeout_ns);
+	return xhci_get_timeout_no_hub_lpm(udev, USB3_LPM_U1);
+}
+
+/* Returns the hub-encoded U2 timeout value.
+ * The U2 timeout should be the maximum of:
+ *  - 10 ms (to avoid the bandwidth impact on the scheduler)
+ *  - largest bInterval of any active periodic endpoint (to avoid going
+ *    into lower power link states between intervals).
+ *  - the U2 Exit Latency of the device
+ */
+static u16 xhci_calculate_intel_u2_timeout(struct usb_device *udev,
+		struct usb_endpoint_descriptor *desc)
+{
+	unsigned long long timeout_ns;
+	unsigned long long u2_del_ns;
+
+	timeout_ns = 10 * 1000 * 1000;
+
+	if ((usb_endpoint_xfer_int(desc) || usb_endpoint_xfer_isoc(desc)) &&
+			(xhci_service_interval_to_ns(desc) > timeout_ns))
+		timeout_ns = xhci_service_interval_to_ns(desc);
+
+	u2_del_ns = udev->bos->ss_cap->bU2DevExitLat * 1000;
+	if (u2_del_ns > timeout_ns)
+		timeout_ns = u2_del_ns;
+
+	/* The U2 timeout is encoded in 256us intervals */
+	timeout_ns = DIV_ROUND_UP(timeout_ns, 256 * 1000);
+	/* If the necessary timeout value is bigger than what we can set in the
+	 * USB 3.0 hub, we have to disable hub-initiated U2.
+	 */
+	if (timeout_ns <= USB3_LPM_U2_MAX_TIMEOUT)
+		return timeout_ns;
+	dev_dbg(&udev->dev, "Hub-initiated U2 disabled "
+			"due to long timeout %llu ms\n", timeout_ns);
+	return xhci_get_timeout_no_hub_lpm(udev, USB3_LPM_U2);
+}
+
+static u16 xhci_call_host_update_timeout_for_endpoint(struct xhci_hcd *xhci,
+		struct usb_device *udev,
+		struct usb_endpoint_descriptor *desc,
+		enum usb3_link_state state,
+		u16 *timeout)
+{
+	if (state == USB3_LPM_U1) {
+		if (xhci->quirks & XHCI_INTEL_HOST)
+			return xhci_calculate_intel_u1_timeout(udev, desc);
+	} else {
+		if (xhci->quirks & XHCI_INTEL_HOST)
+			return xhci_calculate_intel_u2_timeout(udev, desc);
+	}
+
+	return USB3_LPM_DISABLED;
+}
+
+static int xhci_update_timeout_for_endpoint(struct xhci_hcd *xhci,
+		struct usb_device *udev,
+		struct usb_endpoint_descriptor *desc,
+		enum usb3_link_state state,
+		u16 *timeout)
+{
+	u16 alt_timeout;
+
+	alt_timeout = xhci_call_host_update_timeout_for_endpoint(xhci, udev,
+		desc, state, timeout);
+
+	/* If we found we can't enable hub-initiated LPM, or
+	 * the U1 or U2 exit latency was too high to allow
+	 * device-initiated LPM as well, just stop searching.
+	 */
+	if (alt_timeout == USB3_LPM_DISABLED ||
+			alt_timeout == USB3_LPM_DEVICE_INITIATED) {
+		*timeout = alt_timeout;
+		return -E2BIG;
+	}
+	if (alt_timeout > *timeout)
+		*timeout = alt_timeout;
+	return 0;
+}
+
+static int xhci_update_timeout_for_interface(struct xhci_hcd *xhci,
+		struct usb_device *udev,
+		struct usb_host_interface *alt,
+		enum usb3_link_state state,
+		u16 *timeout)
+{
+	int j;
+
+	for (j = 0; j < alt->desc.bNumEndpoints; j++) {
+		if (xhci_update_timeout_for_endpoint(xhci, udev,
+					&alt->endpoint[j].desc, state, timeout))
+			return -E2BIG;
+		continue;
+	}
+	return 0;
+}
+
+static int xhci_check_intel_tier_policy(struct usb_device *udev,
+		enum usb3_link_state state)
+{
+	struct usb_device *parent;
+	unsigned int num_hubs;
+
+	if (state == USB3_LPM_U2)
+		return 0;
+
+	/* Don't enable U1 if the device is on a 2nd tier hub or lower. */
+	for (parent = udev->parent, num_hubs = 0; parent->parent;
+			parent = parent->parent)
+		num_hubs++;
+
+	if (num_hubs < 2)
+		return 0;
+
+	dev_dbg(&udev->dev, "Disabling U1 link state for device"
+			" below second-tier hub.\n");
+	dev_dbg(&udev->dev, "Plug device into first-tier hub "
+			"to decrease power consumption.\n");
+	return -E2BIG;
+}
+
+static int xhci_check_tier_policy(struct xhci_hcd *xhci,
+		struct usb_device *udev,
+		enum usb3_link_state state)
+{
+	if (xhci->quirks & XHCI_INTEL_HOST)
+		return xhci_check_intel_tier_policy(udev, state);
+	return -EINVAL;
+}
+
+/* Returns the U1 or U2 timeout that should be enabled.
+ * If the tier check or timeout setting functions return with a non-zero exit
+ * code, that means the timeout value has been finalized and we shouldn't look
+ * at any more endpoints.
+ */
+static u16 xhci_calculate_lpm_timeout(struct usb_hcd *hcd,
+			struct usb_device *udev, enum usb3_link_state state)
+{
+	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
+	struct usb_host_config *config;
+	char *state_name;
+	int i;
+	u16 timeout = USB3_LPM_DISABLED;
+
+	if (state == USB3_LPM_U1)
+		state_name = "U1";
+	else if (state == USB3_LPM_U2)
+		state_name = "U2";
+	else {
+		dev_warn(&udev->dev, "Can't enable unknown link state %i\n",
+				state);
+		return timeout;
+	}
+
+	if (xhci_check_tier_policy(xhci, udev, state) < 0)
+		return timeout;
+
+	/* Gather some information about the currently installed configuration
+	 * and alternate interface settings.
+	 */
+	if (xhci_update_timeout_for_endpoint(xhci, udev, &udev->ep0.desc,
+			state, &timeout))
+		return timeout;
+
+	config = udev->actconfig;
+	if (!config)
+		return timeout;
+
+	for (i = 0; i < USB_MAXINTERFACES; i++) {
+		struct usb_driver *driver;
+		struct usb_interface *intf = config->interface[i];
+
+		if (!intf)
+			continue;
+
+		/* Check if any currently bound drivers want hub-initiated LPM
+		 * disabled.
+		 */
+		if (intf->dev.driver) {
+			driver = to_usb_driver(intf->dev.driver);
+			if (driver && driver->disable_hub_initiated_lpm) {
+				dev_dbg(&udev->dev, "Hub-initiated %s disabled "
+						"at request of driver %s\n",
+						state_name, driver->name);
+				return xhci_get_timeout_no_hub_lpm(udev, state);
+			}
+		}
+
+		/* Not sure how this could happen... */
+		if (!intf->cur_altsetting)
+			continue;
+
+		if (xhci_update_timeout_for_interface(xhci, udev,
+					intf->cur_altsetting,
+					state, &timeout))
+			return timeout;
+	}
+	return timeout;
+}
+
+/*
+ * Issue an Evaluate Context command to change the Maximum Exit Latency in the
+ * slot context.  If that succeeds, store the new MEL in the xhci_virt_device.
+ */
+static int xhci_change_max_exit_latency(struct xhci_hcd *xhci,
+			struct usb_device *udev, u16 max_exit_latency)
+{
+	struct xhci_virt_device *virt_dev;
+	struct xhci_command *command;
+	struct xhci_input_control_ctx *ctrl_ctx;
+	struct xhci_slot_ctx *slot_ctx;
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	if (max_exit_latency == xhci->devs[udev->slot_id]->current_mel) {
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return 0;
+	}
+
+	/* Attempt to issue an Evaluate Context command to change the MEL. */
+	virt_dev = xhci->devs[udev->slot_id];
+	command = xhci->lpm_command;
+	xhci_slot_copy(xhci, command->in_ctx, virt_dev->out_ctx);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	ctrl_ctx = xhci_get_input_control_ctx(xhci, command->in_ctx);
+	ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
+	slot_ctx = xhci_get_slot_ctx(xhci, command->in_ctx);
+	slot_ctx->dev_info2 &= cpu_to_le32(~((u32) MAX_EXIT));
+	slot_ctx->dev_info2 |= cpu_to_le32(max_exit_latency);
+
+	xhci_dbg(xhci, "Set up evaluate context for LPM MEL change.\n");
+	xhci_dbg(xhci, "Slot %u Input Context:\n", udev->slot_id);
+	xhci_dbg_ctx(xhci, command->in_ctx, 0);
+
+	/* Issue and wait for the evaluate context command. */
+	ret = xhci_configure_endpoint(xhci, udev, command,
+			true, true);
+	xhci_dbg(xhci, "Slot %u Output Context:\n", udev->slot_id);
+	xhci_dbg_ctx(xhci, virt_dev->out_ctx, 0);
+
+	if (!ret) {
+		spin_lock_irqsave(&xhci->lock, flags);
+		virt_dev->current_mel = max_exit_latency;
+		spin_unlock_irqrestore(&xhci->lock, flags);
+	}
+	return ret;
+}
+
+static int calculate_max_exit_latency(struct usb_device *udev,
+		enum usb3_link_state state_changed,
+		u16 hub_encoded_timeout)
+{
+	unsigned long long u1_mel_us = 0;
+	unsigned long long u2_mel_us = 0;
+	unsigned long long mel_us = 0;
+	bool disabling_u1;
+	bool disabling_u2;
+	bool enabling_u1;
+	bool enabling_u2;
+
+	disabling_u1 = (state_changed == USB3_LPM_U1 &&
+			hub_encoded_timeout == USB3_LPM_DISABLED);
+	disabling_u2 = (state_changed == USB3_LPM_U2 &&
+			hub_encoded_timeout == USB3_LPM_DISABLED);
+
+	enabling_u1 = (state_changed == USB3_LPM_U1 &&
+			hub_encoded_timeout != USB3_LPM_DISABLED);
+	enabling_u2 = (state_changed == USB3_LPM_U2 &&
+			hub_encoded_timeout != USB3_LPM_DISABLED);
+
+	/* If U1 was already enabled and we're not disabling it,
+	 * or we're going to enable U1, account for the U1 max exit latency.
+	 */
+	if ((udev->u1_params.timeout != USB3_LPM_DISABLED && !disabling_u1) ||
+			enabling_u1)
+		u1_mel_us = DIV_ROUND_UP(udev->u1_params.mel, 1000);
+	if ((udev->u2_params.timeout != USB3_LPM_DISABLED && !disabling_u2) ||
+			enabling_u2)
+		u2_mel_us = DIV_ROUND_UP(udev->u2_params.mel, 1000);
+
+	if (u1_mel_us > u2_mel_us)
+		mel_us = u1_mel_us;
+	else
+		mel_us = u2_mel_us;
+	/* xHCI host controller max exit latency field is only 16 bits wide. */
+	if (mel_us > MAX_EXIT) {
+		dev_warn(&udev->dev, "Link PM max exit latency of %lluus "
+				"is too big.\n", mel_us);
+		return -E2BIG;
+	}
+	return mel_us;
+}
+
+/* Returns the USB3 hub-encoded value for the U1/U2 timeout. */
+int xhci_enable_usb3_lpm_timeout(struct usb_hcd *hcd,
+			struct usb_device *udev, enum usb3_link_state state)
+{
+	struct xhci_hcd	*xhci;
+	u16 hub_encoded_timeout;
+	int mel;
+	int ret;
+
+	xhci = hcd_to_xhci(hcd);
+	/* The LPM timeout values are pretty host-controller specific, so don't
+	 * enable hub-initiated timeouts unless the vendor has provided
+	 * information about their timeout algorithm.
+	 */
+	if (!xhci || !(xhci->quirks & XHCI_LPM_SUPPORT) ||
+			!xhci->devs[udev->slot_id])
+		return USB3_LPM_DISABLED;
+
+	hub_encoded_timeout = xhci_calculate_lpm_timeout(hcd, udev, state);
+	mel = calculate_max_exit_latency(udev, state, hub_encoded_timeout);
+	if (mel < 0) {
+		/* Max Exit Latency is too big, disable LPM. */
+		hub_encoded_timeout = USB3_LPM_DISABLED;
+		mel = 0;
+	}
+
+	ret = xhci_change_max_exit_latency(xhci, udev, mel);
+	if (ret)
+		return ret;
+	return hub_encoded_timeout;
+}
+
+int xhci_disable_usb3_lpm_timeout(struct usb_hcd *hcd,
+			struct usb_device *udev, enum usb3_link_state state)
+{
+	struct xhci_hcd	*xhci;
+	u16 mel;
+	int ret;
+
+	xhci = hcd_to_xhci(hcd);
+	if (!xhci || !(xhci->quirks & XHCI_LPM_SUPPORT) ||
+			!xhci->devs[udev->slot_id])
+		return 0;
+
+	mel = calculate_max_exit_latency(udev, state, USB3_LPM_DISABLED);
+	ret = xhci_change_max_exit_latency(xhci, udev, mel);
+	if (ret)
+		return ret;
+	return 0;
+}
+/*-------------------------------------------------------------------------*/
+
 int xhci_update_device(struct usb_hcd *hcd, struct usb_device *udev)
 {
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index ce1edd7246aa..de3d6e3e57be 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -362,8 +362,10 @@ struct xhci_op_regs {
  * Timeout can be up to 127us.  0xFF means an infinite timeout.
  */
 #define PORT_U1_TIMEOUT(p)	((p) & 0xff)
+#define PORT_U1_TIMEOUT_MASK	0xff
 /* Inactivity timer value for transitions into U2 */
 #define PORT_U2_TIMEOUT(p)	(((p) & 0xff) << 8)
+#define PORT_U2_TIMEOUT_MASK	(0xff << 8)
 /* Bits 24:31 for port testing */
 
 /* USB2 Protocol PORTSPMSC */
@@ -914,6 +916,8 @@ struct xhci_virt_device {
 	u8				real_port;
 	struct xhci_interval_bw_table	*bw_table;
 	struct xhci_tt_bw_info		*tt_info;
+	/* The current max exit latency for the enabled USB3 link states. */
+	u16				current_mel;
 };
 
 /*
@@ -1424,6 +1428,8 @@ struct xhci_hcd {
 	/* slot enabling and address device helpers */
 	struct completion	addr_dev;
 	int slot_id;
+	/* For USB 3.0 LPM enable/disable. */
+	struct xhci_command		*lpm_command;
 	/* Internal mirror of the HW's dcbaa */
 	struct xhci_virt_device	*devs[MAX_HC_SLOTS];
 	/* For keeping track of bandwidth domains per roothub. */
@@ -1481,6 +1487,9 @@ struct xhci_hcd {
 #define XHCI_RESET_ON_RESUME	(1 << 7)
 #define	XHCI_SW_BW_CHECKING	(1 << 8)
 #define XHCI_AMD_0x96_HOST	(1 << 9)
+#define XHCI_TRUST_TX_LENGTH	(1 << 10)
+#define XHCI_LPM_SUPPORT	(1 << 11)
+#define XHCI_INTEL_HOST		(1 << 12)
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
 	/* There are two roothubs to keep track of bus suspend info for */
@@ -1754,7 +1763,7 @@ int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, gfp_t mem_flags,
 int xhci_queue_configure_endpoint(struct xhci_hcd *xhci, dma_addr_t in_ctx_ptr,
 		u32 slot_id, bool command_must_succeed);
 int xhci_queue_evaluate_context(struct xhci_hcd *xhci, dma_addr_t in_ctx_ptr,
-		u32 slot_id);
+		u32 slot_id, bool command_must_succeed);
 int xhci_queue_reset_ep(struct xhci_hcd *xhci, int slot_id,
 		unsigned int ep_index);
 int xhci_queue_reset_device(struct xhci_hcd *xhci, u32 slot_id);
@@ -1778,6 +1787,10 @@ void xhci_ring_ep_doorbell(struct xhci_hcd *xhci, unsigned int slot_id,
 /* xHCI roothub code */
 void xhci_set_link_state(struct xhci_hcd *xhci, __le32 __iomem **port_array,
 				int port_id, u32 link_state);
+int xhci_enable_usb3_lpm_timeout(struct usb_hcd *hcd,
+			struct usb_device *udev, enum usb3_link_state state);
+int xhci_disable_usb3_lpm_timeout(struct usb_hcd *hcd,
+			struct usb_device *udev, enum usb3_link_state state);
 void xhci_test_and_clear_bit(struct xhci_hcd *xhci, __le32 __iomem **port_array,
 				int port_id, u32 port_bit);
 int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue, u16 wIndex,