linux-kernel - Re: [PATCH V3 5/5] input: pxa27x-keypad: add device tree support

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Message-ID: <CADApbehrJ=Jy_Z57serKuDm+-6_oy94QbrJUxL17HCKokDov8A@mail.gmail.com>
Date:	Thu, 20 Jun 2013 10:01:24 +0800
From:	Chao Xie <xiechao.mail@...il.com>
To:	Chao Xie <xiechao.mail@...il.com>, Marek Vasut <marex@...x.de>,
	stefan@...nezx.org, Eric Miao <eric.y.miao@...il.com>,
	Arnd Bergmann <arnd@...db.de>, slapin@...fans.org,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Haojian Zhuang <haojian.zhuang@...il.com>,
	Chao Xie <chao.xie@...vell.com>, laforge@...nezx.org,
	linux-input@...r.kernel.org, sleep_walker@...e.cz,
	Robert Jarzmik <robert.jarzmik@...e.fr>, drwyrm@...il.com,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V3 5/5] input: pxa27x-keypad: add device tree support

On Wed, Jun 19, 2013 at 7:13 PM, Gerhard Sittig <gsi@...x.de> wrote:
> On Wed, Jun 19, 2013 at 16:38 +0800, Chao Xie wrote:
>>
>> On Wed, Jun 19, 2013 at 4:22 PM, Marek Vasut <marex@...x.de> wrote:
>> >
>> >> Signed-off-by: Chao Xie <chao.xie@...vell.com>
>> >> [ ... ]
>> >> +++ b/Documentation/devicetree/bindings/input/pxa27x-keypad.txt
>> >> @@ -0,0 +1,60 @@
>> >> +* Marvell PXA Keypad controller
>> >> +
>> >> +Required Properties
>> >> +- compatible : should be "marvell,pxa27x-keypad"
>> >> +- reg : Address and length of the register set for the device
>> >> +- interrupts : The interrupt for the keypad controller
>> >> +- marvell,debounce-interval : How long time the key will be
>> >
>> > Is there no generic prop name for this debounce interval?
>> >
>> I searched at drivers/input and Documents.
>> Two drivers use "debounce-interval", gpio-keys.c and stmpe-keypad.c.
>> They describe the meanings of "debounce-interval" at its own document file.
>> Some other drivers uses "xxx,debounce-delay-ms" or "debounce-delay-ms"
>> So it seems that there is no generic prop name for this debounce interval.
>
> Actually there is, but under a different (more user friendly)
> name:  See the 'debounce-delay-ms' property in
> Documentation/devicetree/bindings/input/gpio-matrix-keypad.txt
> which gets referenced in the matrix_keypad_parse_dt() routine in
> the drivers/input/keyboard/matrix_keypad.c source file.  Ah, your
> last sentence mentions that fact.
>
> But when you introduce DT support into an existing driver which
> previously used platform data, then there is no problem with
> backwards compatibility in .dts files.  So I suggest to go with
> the "debounce-delay-ms" name since it better reflects to the .dts
> author (hardware engineer) which unit the number is supposed to
> be specified in.
>
So Arnd
What do you think? I am fine with either one.

>
> Note that I've recently worked on extending the matrix keypad
> input driver (doc improvements, software polling, binary encoded
> column selection), but haven't submitted the patch series yet
> since it's perfectly operational on the target which motivated
> the extension but wasn't tested yet on any other platform or
> matrix setup -- I currently lack access to an ARM based board
> with either lots of accessible GPIOs to connect a matrix to, or
> some matrix already built into the board, but more importantly
> lack free resources for this very driver extension.
>
> Alternatively I might send an RFC series since the current state
> isn't good enough for v1.  Just ask if you'd like to test or
> review what I have come up with so far (it builds but wasn't
> run-tested).
>
Sure, i can help you to test at PXA platform which is ARM based.

>
> virtually yours
> Gerhard Sittig
> --
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
> HRB 165235 Munich, Office: Kirchenstr. 5, D-82194 Groebenzell, Germany
> Phone: +49-8142-66989-0 Fax: +49-8142-66989-80  Email: office@...x.de
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