On Thu, 31 Aug 2006, Rodolfo Giometti wrote: > On Thu, Aug 31, 2006 at 03:36:42AM -0700, David Brownell wrote: > > > > USB on many system-on-chip processors also has less aggressive sleep > > states, where for example USB port power might be maintained, and > > the root hub clocked enough to detect simple events like "remote > > wakeup", "connect new device", and "disconnect device" ... and then > > use those as system wakeup events. > > Not my case since the CPU goes in a power-off mode and can be resumed > only throught few pins.
Dave was talking about USB port power, not CPU power. Unless the USB ports are driven directly by the CPU (which they might be in your case), it might be possible to keep the ports powered on even while the CPU is powered off. > > That's correct for the "power fully off" mode, yes. Maybe you can > > So, no way to have a rootfs on a USBkey and the suspend/resume > support. Not if the USB ports lose power during the suspend. That's equivalent to keeping your rootfs on a USB key and then unplugging the key. It just won't work. > > do better than that; see how ohci-at91.c will keep USB active during > > "standby" sleep, that's the best in-tree example today. > > It disables only the clocks... it seems a "poor" suspend/resume > support... Better than nothing. What else would you like to disable? > > But in general, userspace should be assuming that all removable > > media will have been removed by the time the system comes back up, > > and have prepared for it. Unmounting would be a nice safe policy, > > but if userspace knows the system will sleep and is _not_ ready for > > the media to be removed, that's a userspace bug. > > Mmm... it doesn't seem so flexible. What happens if umount fails? I > can't suspend the system? :-o Well, you can still suspend the system. You just won't be able to use the mounted filesystem after resuming. :-) Like I said before, this situation is no different from unplugging the USB device during the suspend and then plugging it back in after the resume. Alan Stern ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
