Re: Enable CONFIG_USB_SUSPEND by default or some mobile HD can't be unplugged safely

On Thu, 1 Jan 2009, Alexander E. Patrakov wrote:

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." 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.

You have obviously tested only Windows XP, because Vista doesn't cut the
power for at least some USB devices.

Yan never said that Windows cuts any power; he only said that the light
turns off. This is accomplished by disabling the USB port, not by
cutting power.

And congratulations for obtaining a
Vista-incompatible hard drive (of course, joking).

BTW, does the "eject /dev/$DEV" command help?

I wouldn't expect it to help, since it doesn't disable the port or put
the device into suspend mode.

Alan Stern

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Relevant Pages