On Wed, 7 Dec 2005, Harry Butterworth wrote: > > Suspend/resume is liable to cause trouble. For instance, what happens to > > the various front-ends if the back-end decides to suspend a USB device? > > I don't know. Could you explain this scenario in more detail (imagine > that none of the 800 page USB spec sunk in when I read it :-). What > should happen in this case?
Suspend and reset are both troublemakers, because they act not on a device but on the device's parent hub. However resets are pretty self-contained, so provided you recognize them and handle them properly you should be okay. The back-end won't reset a device all by itself. The problems with USB suspend are just a small subset of the problems with suspend in general. What happens to a front-end if a back-end goes to sleep, for example? Your best approach is to make sure that a back-end never tries to suspend an exported device. Then the front-end will be completely responsible for device power management, and no confusion will arise. Alan Stern ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
