linux-kernel - Re: [PATCH 4/5] input: tc3589x-keypad: support probing from device tree

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Date:	Fri, 1 Nov 2013 09:08:41 -0700
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Mark Rutland <mark.rutland@....com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH 4/5] input: tc3589x-keypad: support probing from device tree

On Thu, Oct 31, 2013 at 5:58 PM, Mark Rutland <mark.rutland@....com> wrote:

>> +     plat = devm_kzalloc(dev, sizeof(*plat), GFP_KERNEL);
>> +     if (!plat)
>> +             return ERR_PTR(-ENOMEM);
>> +
>> +     of_property_read_u8(np, "keypad,num-columns", &plat->kcol);
>> +     of_property_read_u8(np, "keypad,num-rows", &plat->krow);
>
> These look wrong to me, as almost every single use of of_property_read_u8 (or
> of_property_read_u16) do. They read _packed_ values out of the dt, and do not
> read (u32) cells as u8s or u16s.

Yes...

> The matrix-keymap binding doesn't define these as 8-bit, and the example
> binding they are u32 cells. Either the binding document or this code is wrong.

The biding is in patch titled:
"mfd: tc3589x: Add device tree bindings"
and yes, you are right, this seems wrong. (The example in that patch
is wrong too.)

> I'm confused as to how this can work. Are you using /bits/ 8 in your dts?

Yes indeed I do. So it was working fine...

I'll adjust this to use u32:s, even if it seems odd supporting keypads
with 255+ columns and rows... well it's in there.

Yours,
Linus Walleij
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