linux-kernel - Re: [PATCH] HID: usbhid: get/put around clearing needs_remote

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Date:	Mon, 24 Nov 2014 10:13:15 +0100
From:	Oliver Neukum <oneukum@...e.de>
To:	Benson Leung <bleung@...omium.org>
Cc:	johan@...nel.org, Jiri Kosina <jkosina@...e.cz>,
	linux-usb@...r.kernel.org,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Sameer Nanda <snanda@...omium.org>
Subject: Re: [PATCH] HID: usbhid: get/put around clearing needs_remote_wakeup

On Fri, 2014-11-21 at 17:00 -0800, Benson Leung wrote:

> If devices are already asleep with this flag enabled, that means that
> they are presently configured for remote wake.

Yes, but that doesn't matter. The drivers must be ready for a device
being resumed at any time. Remote wakeup just adds one more reason.

> Waking the device in the case of a close() is appropriate because it
> also has the effect of re-suspending the device with the capability
> disabled, as it is no longer necessary.

But there is very little to be gained by switching off remote wakeup.
The additional energy consumption devices with remote wakeup enabled
will be dwarfed by the energy needed for an additional wakeup.

	Regards
		Oliver


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