On Wed, 25 Jul 2018, Kai-Heng Feng wrote: > In order to let host's parent device, rtsx_usb, to use USB remote wake > up signaling to do card detection, it needs to be suspended. Hence it's > necessary to add runtime PM support for the memstick host. > > To keep memstick host stays suspended when it's not in use, convert the > card detection function from kthread to delayed_work, which can be > scheduled when the host is resumed and can be canceled when the host is > suspended. > > Use an idle function check if there's no card and the power mode is > MEMSTICK_POWER_OFF. If both criteria are met, put the device to suspend. > > Signed-off-by: Kai-Heng Feng <[email protected]>
I'm not familiar enough with this driver to comment on specific instances, but you should carefully go through the code and make sure that you use pm_runtime_get_noresume() and pm_runtime_put_noidle() correctly. The basic idea is to use these when you know beforehand that the device is already at full power (for _get_noresume) and the usage count will not go to 0 (for _put_noidle). If you aren't certain of these requirements then you should call pm_runtime_get_sync() and pm_runtime_put(). Alan Stern
