From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752369AbdJaNQV (ORCPT <rfc822;w@1wt.eu>);
        Tue, 31 Oct 2017 09:16:21 -0400
Received: from vps0.lunn.ch ([185.16.172.187]:35050 "EHLO vps0.lunn.ch"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751050AbdJaNQT (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 31 Oct 2017 09:16:19 -0400
Date: Tue, 31 Oct 2017 14:16:17 +0100
From: Andrew Lunn <andrew@lunn.ch>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>,
        "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jason Cooper <jason@lakedaemon.net>,
        Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        Antoine Tenart <antoine.tenart@free-electrons.com>,
        =?iso-8859-1?Q?Miqu=E8l?= Raynal 
        <miquel.raynal@free-electrons.com>,
        Nadav Haklai <nadavh@marvell.com>, Victor Gu <xigu@marvell.com>,
        Marcin Wojtas <mw@semihalf.com>, Wilson Ding <dingwei@marvell.com>,
        Hua Jing <jinghua@marvell.com>,
        Neta Zur Hershkovits <neta@marvell.com>, Ken Ma <make@marvell.com>
Subject: Re: [PATCH] pinctrl: armada-37xx: Add edge both type gpio irq support
Message-ID: <20171031131617.GA11647@lunn.ch>
References: <20171019131003.9684-1-gregory.clement@free-electrons.com>
 <CACRpkdbqjh5U5QoE_B+7GfSyDdHW-NCAvogGq-2n8j6L6nG-Gw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CACRpkdbqjh5U5QoE_B+7GfSyDdHW-NCAvogGq-2n8j6L6nG-Gw@mail.gmail.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> Patch applied.
> 
> The discussion here is interesting, it is customary for GPIO drivers
> to implement double-edge detection emulation by swapping the
> edge detector around like this.

Hi Linus

I was not aware this was customary.

> It might be possible to collect some generic information about
> this in the Documentation/gpio/driver.txt document.

Yes, i think it should be documented somewhere. Even in the use case
here, detecting an SD card being inserted/removed, you could get some
bounce on the microswitch, miss an edge, and be in the wrong state.

       Andrew