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()
4047 	"U2",
4053  * device-initiated U1 or U2.  This lets the device know the exit latencies from
4054  * the time the device initiates a U1 or U2 exit, to the time it will receive a
4084 	 * U1/U2 when the exit latencies are too high.  in usb_req_set_sel()
4090 		dev_dbg(&udev->dev, "Device-initiated U1/U2 disabled due to long SEL or PEL\n");  in usb_req_set_sel()
4123  * Enable or disable device-initiated U1 or U2 transitions.
4139 		dev_warn(&udev->dev, "%s: Can't %s non-U1 or U2 state.\n",  in usb_set_device_initiated_lpm()
4155 		 * for either U1 or U2.  in usb_set_device_initiated_lpm()
4194 		dev_warn(&udev->dev, "%s: Can't set timeout for non-U1 or U2 state.\n",  in usb_set_lpm_timeout()
4224  * Don't allow device intiated U1/U2 if the system exit latency + one bus
4268  * Enable the hub-initiated U1/U2 idle timeouts, and enable device-initiated
4269  * U1/U2 entry.
4271  * We will attempt to enable U1 or U2, but there are no guarantees that the
4272  * control transfers to set the hub timeout or enable device-initiated U1/U2
4275  * If the control transfer to enable device-initiated U1/U2 entry fails, then
4276  * hub-initiated U1/U2 will be disabled.
4278  * If we cannot set the parent hub U1/U2 timeout, we attempt to let the xHCI
4280  * take up more slightly more bus bandwidth for unnecessary U1/U2 exit latency.
4297 	 * U1 or U2, it's probably lying.  Assume it doesn't implement that link  in usb_enable_link_state()
4304 	/* We allow the host controller to set the U1/U2 timeout internally  in usb_enable_link_state()
4323 		/* If we can't set the parent hub U1/U2 timeout,  in usb_enable_link_state()
4338 			 * Request to enable device initiated U1/U2 failed,  in usb_enable_link_state()
4353  * Disable the hub-initiated U1/U2 idle timeouts, and disable device-initiated
4354  * U1/U2 entry.
4356  * If this function returns -EBUSY, the parent hub will still allow U1/U2 entry.
4357  * If zero is returned, the parent will not allow the link to go into U1/U2.
4359  * If zero is returned, device-initiated U1/U2 entry may still be enabled, but
4361  * still disallow device-initiated U1/U2 entry.
4363  * If zero is returned, the xHCI host controller may still think U1/U2 entry is
4365  * (to account for U1/U2 exit latency), but it should be harmless.
4375 		dev_warn(&udev->dev, "%s: Can't disable non-U1 or U2 state.\n",  in usb_disable_link_state()
4391 	 * is disabled. Hub will disallows link to enter U1/U2 as well,  in usb_disable_link_state()
4405  * Disable hub-initiated and device-initiated U1 and U2 entry.
4461  * Attempt to enable device-initiated and hub-initiated U1 and U2 entry.  The
4462  * xHCI host policy may prevent U1 or U2 from being enabled.
4464  * Other callers may have disabled link PM, so U1 and U2 entry will be disabled
4483 	 * Device must be configured to accept set feature U1/U2 timeout.  in usb_enable_lpm()