Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Mattijs Korpershoek <mkorpershoek@baylibre.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     linux-kernel@vger.kernel.org, linux-input@vger.kernel.org,
        Fabien Parent <parent.f@gmail.com>, devicetree@vger.kernel.org,
        linux-mediatek@lists.infradead.org,
        Fabien Parent <fparent@baylibre.com>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v1 3/6] dt-bindings: mediatek,mt6779-keypad: add
 mediatek,double-keys
In-Reply-To: <98ec7967-d007-46d7-ef54-aa41426b5f9f@linaro.org>
References: <20220720-mt8183-keypad-v1-0-ef9fc29dbff4@baylibre.com>
 <20220720-mt8183-keypad-v1-3-ef9fc29dbff4@baylibre.com>
 <98ec7967-d007-46d7-ef54-aa41426b5f9f@linaro.org>
Date:   Thu, 21 Jul 2022 15:32:41 +0200
Message-ID: <87r12eh9qe.fsf@baylibre.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Wed, Jul 20, 2022 at 19:26, Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:

> On 20/07/2022 16:48, Mattijs Korpershoek wrote:
>> MediaTek keypad has 2 modes of detecting key events:
>> - single key: each (row, column) can detect one key
>> - double key: each (row, column) is a group of 2 keys
>> 
>> Currently, only single key detection is supported (by default)
>> Add an optional property, mediatek,double-keys to support double
>> key detection.
>
> You focus here on driver implementation and behavior, but should rather
> focus on hardware, like - in such setup two keys are physically wired to
> one (row,column) pin.

Understood. Will reword in v2 to reflect that this is hardware
description, not a software feature.

>
>> 
>> Double key support exists to minimize cost, since it reduces the number
>> of pins required for physical keys.
>> 
>> Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
>> 
>> diff --git a/Documentation/devicetree/bindings/input/mediatek,mt6779-keypad.yaml b/Documentation/devicetree/bindings/input/mediatek,mt6779-keypad.yaml
>> index ca8ae40a73f7..03c9555849e5 100644
>> --- a/Documentation/devicetree/bindings/input/mediatek,mt6779-keypad.yaml
>> +++ b/Documentation/devicetree/bindings/input/mediatek,mt6779-keypad.yaml
>> @@ -49,6 +49,12 @@ properties:
>>      maximum: 256
>>      default: 16
>>  
>> +  mediatek,double-keys:
>
> Do you think there could be another MT keypad version with triple-keys?

Of all the SoC's i've worked on (MT8167, MT8183, MT8365, MT8195) I've
never seen a "triple-keys" keypad.

>
>> +    description: |
>> +      use double key matrix instead of single key
>> +      when set, each (row,column) is a group that can detect 2 keys
>> +    type: boolean
>> +
>>  required:
>>    - compatible
>>    - reg
>> 
>
>
> Best regards,
> Krzysztof