On Sunday 26 September 2004 8:59 am, Alan Stern wrote: > On Sun, 26 Sep 2004, David Brownell wrote: > > > > Unless I'm mistaken, suspend-to-RAM puts most PCI > > > devices into D3cold. > > > > That'd be a bug. STR isn't supposed to discard state like that; it's > > supposed to leave devices (low-)powered but able to resume > > quickly (give or take a few breaths), not turn them off wholesale. > > Otherwise it'd need to be called suspend-to-disk. :) > > Not as I understand it. The only difference between STR and STD is that > RAM is kept alive and refreshed. Everything else is still turned off. > Maybe you're thinking of Standby -- we should check with Pavel.
I think some of the definitions are system-specific, and all of the relevant specifications are weasel-worded to support that. Key point: if RAM is powered, some devices could be too; and the wakeup devices (USB, network, keyboard, etc) probably need it. What _is_ clear is that deeper suspend levels are expected to take more time during resume. In pretty much all cases. > > There can be whole trees of devices sitting in USB suspend state, which > > will be enabled just fine by correctly resuming the tree. Heck, one of > > them may have just woken the system up ... :) > > Not from a suspend-to-disk! :-) Why not? A particular implementation of STD might not support it. But most motherboards today consume power when "off", and some allocate power to USB specifically to support those wakeup modes. > So resume-from-disk requires detecting, initializing, and enumerating > every USB device, pretty much like usb_reset_device() does now. Only on boards that don't provide USB suspend current. Or where Linux can't leverage it, because ACPI or BIOS support is lacking. - Dave ------------------------------------------------------- This SF.Net email is sponsored by: YOU BE THE JUDGE. Be one of 170 Project Admins to receive an Apple iPod Mini FREE for your judgement on who ports your project to Linux PPC the best. Sponsored by IBM. Deadline: Sept. 24. Go here: http://sf.net/ppc_contest.php _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
