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

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Date:	Tue, 25 Nov 2014 10:53:45 +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 Mon, 2014-11-24 at 16:56 -0800, Benson Leung wrote:
> Hi Oliver,
> 
> On Mon, Nov 24, 2014 at 1:13 AM, Oliver Neukum <oneukum@...e.de> wrote:
> >
> > 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.
> >
> 
> That makes sense to me. Does this mean we should be moving toward a
> solution that doesn't wake suspended devices on close for other usb
> devices, not just hid?
> 
> This particular pattern of get()/needs_remote_wakeup=0/put() on
> close() appears in several other drivers, for example :
> 62ecae0 Input: wacom - properly enable runtime PM
> 5d9efc5 Input: usbtouchscreen - implement runtime power management

Yes, we should never wake up a device just to unset remote
wakeup for runtime PM. In hindsight those patches were clumsy.

	Regards
		Oliver


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