linux-kernel - Re: [PATCH 2/4] Input: mt-matrix-keypad: Add Bosch mt matrix keypad driver

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Date:   Wed, 4 May 2022 16:14:04 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Gireesh.Hiremath@...bosch.com
Cc:     linux-omap@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        bcousson@...libre.com, tony@...mide.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, dmitry.torokhov@...il.com,
        mkorpershoek@...libre.com, davidgow@...gle.com,
        swboyd@...omium.org, fengping.yu@...iatek.com,
        y.oudjana@...tonmail.com, rdunlap@...radead.org,
        colin.king@...el.com, sjoerd.simons@...labora.co.uk,
        VinayKumar.Shettar@...bosch.com,
        Govindaraji.Sivanantham@...bosch.com, anaclaudia.dias@...bosch.com
Subject: Re: [PATCH 2/4] Input: mt-matrix-keypad: Add Bosch mt matrix keypad
 driver

On 22-05-04, Gireesh.Hiremath@...bosch.com wrote:
> From: Gireesh Hiremath <Gireesh.Hiremath@...bosch.com>
> 
> The existing matric_keypad.c use different gpio line for row and colunm,
> where in mt_matrix_kepad.c use same gpio line for row as well as column.
> a key can be placed at each intersection of a unique row number 
> not equal to a unique column and they are diagonally symmetric.
> Advantage of this is with existed gpio line we can get more keys
>   
> example: in matrix_keypad.c for 5 gpio line possible matrix is 2X3 or 3X2
> and maximum possible keys are 6 but 
> in mt_matrix_kepad.c for same 5 gpio line possible matrix is 5X5 and maximum
> possible buttons are 10, below table will discribe that

Nobody should stop you to increase the amount of max. possible keys, so
this isn't a real block.

> 	------------------------------------------------------
> 	|Row\Col |GPIO 0 | GPIO 1 | GPIO 2 | GPIO 3 | GPIO 4 |
> 	------------------------------------------------------
> 	| GPIO 0 |  X    | KEY_9  | KEY_2  | KEY_3  | KEY_1  |
> 	------------------------------------------------------
> 	| GPIO 1 | KEY_9 |  X     | KEY_6  | KEY_5  |  KEY_0 |
> 	------------------------------------------------------
> 	| GPIO 2 | KEY_2 | KEY_6  |  X     | KEY_4  | KEY_7  |
> 	------------------------------------------------------
> 	| GPIO 3 | KEY_3 | KEY_5  | KEY_4  |  X     | KEY_8  |
> 	------------------------------------------------------
> 	| GPIO 4 | KEY_1 |  KEY_0 | KEY_7  | KEY_8  |  X     |
> 	------------------------------------------------------
> 	X - invalid key
> 	KEY_x - preferred key code

That should be pointed somewhere very clearly, thanks for the
description. Also what is than the benefit of the original matrix_keypad
driver?

> both matric_keypad.c and mt_matrix_kepad.c logically operate differently,
> my openion is not to merge both.

IMHO from the user/system-integrator pov it is looking the same and so
one driver should be fine. To distinguish between both modes we could
add dt-property or add a new dt-compatible like "gpio-matrix-keypad-v2".

Regards,
  Marco