From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alan Stern <stern@rowland.harvard.edu>
Subject: Re: Auto suspend not working on usb hid devices
Date: Fri, 16 Jan 2015 10:23:04 -0500 (EST)
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To: vichy <vichy.kuo@gmail.com>
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On Fri, 16 Jan 2015, vichy wrote:

> I found the usb storage interface driver also set supports_autosuspend
> =1 and I found the runtime_usage =1 .
> But the device doesn't go into runtime suspend, even I put control as auto.
> is there any condition purposely abandon usb storage device to do so?

In order to suspend a USB storage device, you have to enable suspend 
not just for that device but also for all its children.  In particular, 
if the device is a disk or flash drive then you have to enable suspend 
for the corresponding SCSI device.

Alan Stern