On Fri, 29 Apr 2005, Oliver Neukum wrote: > > "Provided that you know when you can safely autosuspend." If the driver > > doesn't know when it can suspend its device, who else would know? > > Those who understand the semantics, which with scsi (sg) might be > in user space.
Definitely we wouldn't expect sg to do autosuspend. > > shouldn't make much difference to usb-storage. It doesn't have to tell > > the SCSI layer when the USB transport is suspended. All it has to do is > > resume the USB connection when the next SCSI command comes along. > > No. It has to guarantee that the device will react the same way to the next > command whether a suspension has intervened or not. I really doubt you > can do that for all devices going into power save. How about self-powered USB mass storage devices? Suspending the USB connection generally won't cause these devices to go into a power save mode, although there might be exceptions. However I take your point. Eventually we may expect that the upper layer SCSI drivers sd and sr will autosuspend and will notify their parent when they do so. When usb-storage receives such a notification from below it can then autosuspend safely. Alan Stern ------------------------------------------------------- SF.Net email is sponsored by: Tell us your software development plans! Take this survey and enter to win a one-year sub to SourceForge.net Plus IDC's 2005 look-ahead and a copy of this survey Click here to start! http://www.idcswdc.com/cgi-bin/survey?id=105hix _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
