183 	 * However, there are some that don't, and they set the U1/U2 exit  in usb_device_supports_lpm()
207  * U1/U2, send a PING to the device and receive a PING_RESPONSE.
255  * a transition from either U1 or U2.
378 	 * U2, it's tHubPort2PortExitLat + U2DevExitLat - U1DevExitLat.  I  in usb_set_lpm_parameters()
382 	 * What do we do if the U2 exit latency is less than the U1 exit  in usb_set_lpm_parameters()
4049 	"U2",
4055  * device-initiated U1 or U2.  This lets the device know the exit latencies from
4056  * the time the device initiates a U1 or U2 exit, to the time it will receive a
4086 	 * U1/U2 when the exit latencies are too high.  in usb_req_set_sel()
4092 		dev_dbg(&udev->dev, "Device-initiated U1/U2 disabled due to long SEL or PEL\n");  in usb_req_set_sel()
4125  * Enable or disable device-initiated U1 or U2 transitions.
4141 		dev_warn(&udev->dev, "%s: Can't %s non-U1 or U2 state.\n",  in usb_set_device_initiated_lpm()
4157 		 * for either U1 or U2.  in usb_set_device_initiated_lpm()
4196 		dev_warn(&udev->dev, "%s: Can't set timeout for non-U1 or U2 state.\n",  in usb_set_lpm_timeout()
4226  * Don't allow device intiated U1/U2 if the system exit latency + one bus
4270  * Enable the hub-initiated U1/U2 idle timeouts, and enable device-initiated
4271  * U1/U2 entry.
4273  * We will attempt to enable U1 or U2, but there are no guarantees that the
4274  * control transfers to set the hub timeout or enable device-initiated U1/U2
4277  * If the control transfer to enable device-initiated U1/U2 entry fails, then
4278  * hub-initiated U1/U2 will be disabled.
4280  * If we cannot set the parent hub U1/U2 timeout, we attempt to let the xHCI
4282  * take up more slightly more bus bandwidth for unnecessary U1/U2 exit latency.
4299 	 * U1 or U2, it's probably lying.  Assume it doesn't implement that link  in usb_enable_link_state()
4306 	/* We allow the host controller to set the U1/U2 timeout internally  in usb_enable_link_state()
4325 		/* If we can't set the parent hub U1/U2 timeout,  in usb_enable_link_state()
4340 			 * Request to enable device initiated U1/U2 failed,  in usb_enable_link_state()
4355  * Disable the hub-initiated U1/U2 idle timeouts, and disable device-initiated
4356  * U1/U2 entry.
4358  * If this function returns -EBUSY, the parent hub will still allow U1/U2 entry.
4359  * If zero is returned, the parent will not allow the link to go into U1/U2.
4361  * If zero is returned, device-initiated U1/U2 entry may still be enabled, but
4363  * still disallow device-initiated U1/U2 entry.
4365  * If zero is returned, the xHCI host controller may still think U1/U2 entry is
4367  * (to account for U1/U2 exit latency), but it should be harmless.
4377 		dev_warn(&udev->dev, "%s: Can't disable non-U1 or U2 state.\n",  in usb_disable_link_state()
4393 	 * is disabled. Hub will disallows link to enter U1/U2 as well,  in usb_disable_link_state()
4407  * Disable hub-initiated and device-initiated U1 and U2 entry.
4463  * Attempt to enable device-initiated and hub-initiated U1 and U2 entry.  The
4464  * xHCI host policy may prevent U1 or U2 from being enabled.
4466  * Other callers may have disabled link PM, so U1 and U2 entry will be disabled
4485 	 * Device must be configured to accept set feature U1/U2 timeout.  in usb_enable_lpm()