On Fri, 2 Jan 2009, Yan Li wrote: > Hello List, > > By default CONFIG_USB_SUSPEND is not enabled and today I got bite by > this when I got a new WDC My Book hard drive. I have no way to unplug > it safely, according to it's manual, with a kernel that doesn't have > CONFIG_USB_SUSPEND=y. > > On it's manual read "you should unplug and remove the device only when > the light is off." It's not clear whether you should believe this. The manual may have overstated things. Still, better to be safe. > On Linux unmounting it won't turn it's light off > and I can feel it's motor is still running. The only way to unplug it > properly on a Linux system, as to my knowledge, is to echo `suspend' > to `/sys/bus/usb/devices/$DEV/power/level'. And one has to have > CONFIG_USB_SUSPEND=y to do this. > > On Windows and Mac OS, `safely remove this device' function effectly > turns it into `suspend' mode, and it's light off. Yes -- but they don't suspend the device; instead they disable its upstream port. As far as the device is concerned, there's no difference. However the Linux API doesn't include any way to disable a USB port. Maybe we should add one... > I'm new in this field and I understood people's concern on enabling > autosuspend. As to my understanding, `enabling suspend' and `enabling > autosuspend' should be controlled by two different knobs. They are. > I did a > quick search in LKML and haven't found specific oppose to enable USB > suspend by default, and Debian has started shipping a kernel with > it turned on since 2.6.26. > > Perhaps we should consider turning it on by default? Thanks! That is indeed the next step to take. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
