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Date: Fri, 11 Jan 2013 09:13:43 -0800
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: Simon Glass <sjg@chromium.org>, LKML <linux-kernel@vger.kernel.org>,
        Roland Stigge <stigge@antcom.de>,
        Vincent Palatin <vpalatin@chromium.org>, linux-doc@vger.kernel.org,
        Wolfram Sang <w.sang@pengutronix.de>, Felipe Balbi <balbi@ti.com>,
        Luigi Semenzato <semenzato@chromium.org>,
        Rob Herring <rob.herring@calxeda.com>, linux-input@vger.kernel.org,
        Stephen Warren <swarren@nvidia.com>,
        Sourav Poddar <sourav.poddar@ti.com>,
        Alban Bedel <alban.bedel@avionic-design.de>,
        devicetree-discuss@lists.ozlabs.org,
        Laxman Dewangan <ldewangan@nvidia.com>
Subject: Re: [PATCH v2] input: Extend matrix-keypad device tree binding
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On Fri, Jan 11, 2013 at 10:09:19AM -0700, Stephen Warren wrote:
> On 01/10/2013 06:41 PM, Simon Glass wrote:
> > Some matrix keypad drivers can support different numbers of rows and
> > columns. Add a generic binding for these.
> > 
> > Implementation note:
> > 
> > In order to implement this binding in the kernel, we will need to modify
> > matrix_keypad_() to look up the number of rows and cols in
> > the keymap. Perhaps this could be done by passing 0 for these parameters?
> > Many of the parameters can already be set to NULL. Ick.
> 
> Reviewed-by: Stephen Warren <swarren@nvidia.com>
> 
> Note that the Tegra bindings are based on matrix-keypad.txt, and
> recently added the following properties:
> 
> > - nvidia,kbc-row-pins: The KBC pins which are configured as row. This is an
> >   array of pin numbers which is used as rows.
> > - nvidia,kbc-col-pins: The KBC pins which are configured as column. This is an
> >   array of pin numbers which is used as column.
> 
> Those both define the number of rows/columns (indirectly via the
> property lengths) *and* define which pins are used for the rows/columns.
> How will this influence/interact-with any changes you're planning to the
> core matrix keymap parsing code; would Tegra require your "new"
> keypad,num-rows/keypad,num-columns properties even though the
> information is redundant, or will the Tegra driver have some way of
> passing this information to the core?

Even if we decide to move lookup of keypad,num-rows/keypad,num-columns
into matrix-keypad code we will still allow callers to override DT data,
like we do with platform keymaps.

Thanks.

-- 
Dmitry