From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nick Dyer <nick.dyer@itdev.co.uk>
Subject: Re: [PATCH 22/51] Input: atmel_mxt_ts - Add shutdown function
Date: Wed, 10 Jul 2013 19:32:55 +0100
Message-ID: <51DDA8D7.8010405@itdev.co.uk>
References: <1372337366-9286-1-git-send-email-nick.dyer@itdev.co.uk> <1372337366-9286-23-git-send-email-nick.dyer@itdev.co.uk> <20130707052934.GB15453@core.coreip.homeip.net> <51DA8CB6.2010109@itdev.co.uk> <20130710165509.GC22992@core.coreip.homeip.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Return-path: <linux-input-owner@vger.kernel.org>
Received: from kdh-gw.itdev.co.uk ([89.21.227.133]:43357 "EHLO
	hermes.kdh.itdev.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org
	with ESMTP id S1754538Ab3GJSc6 (ORCPT
	<rfc822;linux-input@vger.kernel.org>);
	Wed, 10 Jul 2013 14:32:58 -0400
In-Reply-To: <20130710165509.GC22992@core.coreip.homeip.net>
Sender: linux-input-owner@vger.kernel.org
List-Id: linux-input@vger.kernel.org
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Daniel Kurtz <djkurtz@chromium.org>, Henrik Rydberg <rydberg@euromail.se>, Joonyoung Shim <jy0922.shim@samsung.com>, Alan Bowens <Alan.Bowens@atmel.com>, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Meerwald <pmeerw@pmeerw.net>, Benson Leung <bleung@chromium.org>, Olof Johansson <olofj@chromium.org>

Dmitry Torokhov wrote:
>> The patch disables the interrupt handler on shutdown.
>>
>> One of our customers reported a bug caused by input events being generated
>> during shutdown (for example if the user was touching the device whilst it
>> was turning off), which was solved by putting in this change.
> 
> What kind of bug? Could you please be more precise?

I did some more digging. Unfortunately the original problem report (some
time around March 2012) was in a customer ticket system that I no longer
have access to. It could well be trying to paper over a problem in their
app layer, to be honest.

>> However, now you've drawn my attention to it again, it seems to me that
>> probably a better thing for us to be doing would be to power off the
>> touchscreen controller here, and let the interrupt disable be handled by
>> core code - do you agree?
> 
> We'd be powering off everything in a moment anyway, no? Or is there a
> concern that the device will stay powered up even if the system is in off
> state?

I agree. I think it's best to not apply this patch for the moment, until we
can prove it's actually required.

Let me know if you want me to generate a new pull request.