On Wed, 14 Mar 2007, Oliver Neukum wrote: > > > Is itr sensible to resume a device which autosuspend had suspended? > > > > Sure. For example, let's say the user writes "-1" to the > > power/autosuspend file. The kernel sets the delay to -1 (thereby > > disabling autosuspend in the future) and wakes up the device. > > > > Or maybe the device sends a remote wakeup request, so the kernel has to > > resume it. > > Or the system wakes up. And all devices sleeping while the system wasn't > suspended wake up. Unless I am mistaken this way you can _increase_ > power consumption if you suspend your system often enough, with enough > devices and long enough a timeout for autosuspend. > And remember, any DMA means no deep sleep states.
That's a separate issue. Right now the PM core tries to make sure that when the system wakes up, devices get resumed only if they weren't suspended when the system went to sleep. This is likely to change in the near future because the data structure that supports it has been deprecated. At that time we will need some way to coordinate the different suspend sources. For now it's okay. The point you raise is quite general; it applies to any subsystem that does runtime power management. You ought to bring it up on linux-pm. Alan Stern P.S.: Even if we leave autosuspend out of the picture, I imagine that constantly suspending and resuming your system would take more power than just letting it sit idle. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
