Device autosuspend is current configured by laptop-mode-tools (LMT), which we intend to replace ( crbug.com/214886 ).
On CrOS autosuspend is a static setting that only needs to be applied once for each device, afterwards it is not changed (e.g. because power is plugged/unplugged). This makes it suitable for replacing it with a set of udev rules instead of doing it in code that needs to be maintained.
For most non-USB devices the kernel enables autosuspend by default, which is the desired behavior. According to the LMT configuration autosuspend should be disabled for a couple of devices (isl29018, cyapa).
For USB autosuspend is disabled by default and we want to enable it explicitly for devices known to support it. The USB whitelist of LMT can be used to generate the corresponding udev rules.
Comment 1 by mka@chromium.org
, Jan 27 2017