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

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Message-ID: <20170911200252.GB41615@decatoncale.mtv.corp.google.com>
Date:   Mon, 11 Sep 2017 13:02:52 -0700
From:   Benson Leung <bleung@...gle.com>
To:     Oliver Neukum <oneukum@...e.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Jiri Kosina <jikos@...nel.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, bleung@...gle.com
Subject: Re: [PATCH] HID: usbhid: get/put around clearing needs_remote_wakeup

Hi Oliver,

On Sat, Sep 09, 2017 at 09:35:52AM +0200, Oliver Neukum wrote:
> Am Freitag, den 08.09.2017, 10:43 -0700 schrieb Dmitry Torokhov:
> > From: Benson Leung <bleung@...omium.org>
> > 
> > usbhid->intf->needs_remote_wakeup is set when a device is opened, and is
> > cleared when a device is closed.
> > 
> > In usbhid_open, usb_autopm_get_interface is called before setting the
> > needs_remote_wakeup flag, and usb_autopm_put_interface is called after
> > hid_start_in. However, when the device is closed in usbhid_close, we
> > simply reset the flag and the device stays awake even though it could be
> > suspended.
> 
> Hi,
> 
> but if the device is asleep, we do not want to wake it just to reset
> the flag. Please use the no resume varieties. They did not exist when this
> code was written and that is the reason behind the current code.
> 

Thanks for the pointer. I'll respin the patch with the no_resume version of
usb_autopm_get_interface and retest.

Benson

-- 
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@...gle.com
Chromium OS Project
bleung@...omium.org

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