Re: Fwd: USB suspending
Alan Stern <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
On Fri, 5 Oct 2007, Oliver Neukum wrote: > Am Freitag 05 Oktober 2007 schrieb Rafael J. Wysocki: > > Hi, > > > > Below is a Lukas' question related to USB suspend that I'm not able to answer. > > > > Please help! > > > > Greetings, > > Rafael > > > > > > ---------- Forwarded Message ---------- > > > > Subject: USB suspending > > Date: Friday, 5 October 2007 14:54 > > From: Lukas Hejtmanek <[email protected]> > > To: "Rafael J. Wysocki" <[email protected]> > > > > Hello, > > > > I've noticed that while suspended in RAM USB ports are powered so any device > > connected to the port gets power. Can I turn off power of all USBs ports while > > suspending to RAM? > > If you do that all devices on these ports will be disconnected. > If you still insist on doing so, it is done by a USB control request. No it isn't. In fact, I think it can't be done at all. For example, many USB controllers don't support PCI power management. None of the controllers on regular desktop and laptop machines support port-power switching. > But power consumption on these ports is minimal for suspended devices, > so it is a bad idea. Right. Power consumption is even smaller on ports with no devices plugged in. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel