Thank you for the kind advice. The "cancel_delayed_work_sync" is essential in case of the operation of kcontrol continuously. We want to make sure the RC clock can be powered up at least 200ms after the speaker volume is adjusted, so we add the "cancel_delayed_work_sync" on the top of the function and requeue it, thanks.
What makes you claim that this is "essential in case of the operation of kcontrol continuously"?
Like the Chrome OS, while the user pull the volume bar up or down, the kcontrol will be manipulated by the UI continuously and seamlessly. In this kind of case, if the "cancel_delayed_work_sync" is removed, the queue_delayed_work will be failed within 200ms after the previous queue_delayed_work, and it will not be able to make sure the power of the RC clock enabled at least 200ms, thanks.