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From: Linus Walleij <linus.walleij@linaro.org>
To: Andrew Lunn <andrew@lunn.ch>
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>,
	"Miquèl 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
Date: Tue, 31 Oct 2017 14:27:13 +0100	[thread overview]
Message-ID: <CACRpkdZxWwXcB8o4+gsYN+mnoQvE7eT5sPOO1mKNuELuo7T70g@mail.gmail.com> (raw)
In-Reply-To: <20171031131617.GA11647@lunn.ch>

On Tue, Oct 31, 2017 at 2:16 PM, Andrew Lunn <andrew@lunn.ch> wrote:

>> 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.

Indeed :/

This is I guess why it is a good idea to combine this with the
debounce feature if the hardware supports it.

I'll think about some writeup.

Yours,
Linus Walleij

WARNING: multiple messages have this Message-ID (diff)
From: linus.walleij@linaro.org (Linus Walleij)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] pinctrl: armada-37xx: Add edge both type gpio irq support
Date: Tue, 31 Oct 2017 14:27:13 +0100	[thread overview]
Message-ID: <CACRpkdZxWwXcB8o4+gsYN+mnoQvE7eT5sPOO1mKNuELuo7T70g@mail.gmail.com> (raw)
In-Reply-To: <20171031131617.GA11647@lunn.ch>

On Tue, Oct 31, 2017 at 2:16 PM, Andrew Lunn <andrew@lunn.ch> wrote:

>> 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.

Indeed :/

This is I guess why it is a good idea to combine this with the
debounce feature if the hardware supports it.

I'll think about some writeup.

Yours,
Linus Walleij

  reply	other threads:[~2017-10-31 13:27 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-19 13:10 [PATCH] pinctrl: armada-37xx: Add edge both type gpio irq support Gregory CLEMENT
2017-10-19 13:10 ` Gregory CLEMENT
2017-10-19 13:38 ` Andrew Lunn
2017-10-19 13:38   ` Andrew Lunn
2017-10-27 12:57   ` Gregory CLEMENT
2017-10-27 12:57     ` Gregory CLEMENT
2017-10-27 19:39     ` Andrew Lunn
2017-10-27 19:39       ` Andrew Lunn
2017-10-31 12:07 ` Linus Walleij
2017-10-31 12:07   ` Linus Walleij
2017-10-31 13:16   ` Andrew Lunn
2017-10-31 13:16     ` Andrew Lunn
2017-10-31 13:27     ` Linus Walleij [this message]
2017-10-31 13:27       ` Linus Walleij
2018-03-20 21:56     ` Uwe Kleine-König
2018-03-20 21:56       ` Uwe Kleine-König
2018-03-20 21:56       ` Uwe Kleine-König
2018-03-21  8:02       ` Linus Walleij
2018-03-21  8:02         ` Linus Walleij
2018-03-21  8:02         ` Linus Walleij

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