_enable_lpm(), which take the bandwidth_mutex before calling usb_disable_lpm() and usb_enable_lpm(), respectively. Introduce a new variable (timeout) in the usb3_lpm_params structure to keep track of the currently enabled U1/U2 timeout values. When usb_disable_lpm() is called, and the USB device has the U1 or U2 timeouts set to a non-zero value (meaning either device-initiated or hub-initiated LPM is enabled), attempt to disable LPM, regardless of the state of the lpm_disable_count. We want to ensure that all callers can be guaranteed that LPM is disabled if usb_disable_lpm() returns zero. Otherwise the following scenario could occur: 1. Driver A is being bound to interface 1. usb_probe_interface() disables LPM. Driver A doesn't care if hub-initiated LPM is enabled, so even though usb_disable_lpm() fails, the probe of the driver continues, and the bandwidth mutex is dropped. 2. Meanwhile, Driver B is being bound to interface 2. usb_probe_interface() grabs the bandwidth mutex and calls usb_disable_lpm(). That call should attempt to disable LPM, even though the lpm_disable_count is set to 1 by Driver A. For usb_enable_lpm(), we attempt to enable LPM only when the lpm_disable_count is zero. If some step in enabling LPM fails, it will only have a minimal impact on power consumption, and all USB device drivers should still work properly. Therefore don't bother to return any error codes. Don't enable device-initiated LPM if the device is unconfigured. The USB device will only accept the U1/U2_ENABLE control transfers in the configured state. Do enable hub-initiated LPM in that case, since devices are allowed to accept the LGO_Ux link commands in any state. Don't enable or disable LPM if the device is marked as not being LPM capable. This can happen if: - the USB device doesn't have a SS BOS descriptor, - the device's parent hub has a zeroed bHeaderDecodeLatency value, or - the xHCI host doesn't support LPM. Signed-off-by: Sarah Sharp Cc: Andiry Xu Cc: Alan Stern Signed-off-by: Sarah Sharp u#ޒ