linux-kernel - Enable CONFIG_USB_SUSPEND by default or some mobile HD can't be unplugged safely

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Date:	Fri, 2 Jan 2009 00:03:43 +0800
From:	Yan Li <elliot.li.tech@...il.com>
To:	gregkh@...e.de, linux-usb@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: Enable CONFIG_USB_SUSPEND by default or some mobile HD can't be
	unplugged safely

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.

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.  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!

-- 
Li, Yan
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