linux-kernel - Re: [PATCH v1 4/6] Input: mt6779-keypad

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Message-ID: <87ilnqh632.fsf@baylibre.com>
Date:   Thu, 21 Jul 2022 16:51:29 +0200
From:   Mattijs Korpershoek <mkorpershoek@...libre.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        Fabien Parent <parent.f@...il.com>, devicetree@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        Fabien Parent <fparent@...libre.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v1 4/6] Input: mt6779-keypad - support double keys matrix

On Thu, Jul 21, 2022 at 10:34, AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com> wrote:

> Il 20/07/22 16:48, Mattijs Korpershoek ha scritto:
>> 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
>> 
>> Double key support exists to minimize cost, since it reduces the number
>> of pins required for physical keys.
>> 
>> Double key is configured by setting BIT(0) of the KP_SEL register.
>> 
>> Enable double key matrix support based on the mediatek,double-keys
>> device tree property.
>> 
>> Signed-off-by: Mattijs Korpershoek <mkorpershoek@...libre.com>
>> Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>
>> 
>> diff --git a/drivers/input/keyboard/mt6779-keypad.c b/drivers/input/keyboard/mt6779-keypad.c
>> index bf447bf598fb..9a5dbd415dac 100644
>> --- a/drivers/input/keyboard/mt6779-keypad.c
>> +++ b/drivers/input/keyboard/mt6779-keypad.c
>> @@ -18,6 +18,7 @@
>>   #define MTK_KPD_DEBOUNCE_MASK	GENMASK(13, 0)
>>   #define MTK_KPD_DEBOUNCE_MAX_MS	256
>>   #define MTK_KPD_SEL		0x0020
>> +#define MTK_KPD_SEL_DOUBLE_KP_MODE	BIT(0)
>>   #define MTK_KPD_SEL_COL	GENMASK(15, 10)
>>   #define MTK_KPD_SEL_ROW	GENMASK(9, 4)
>>   #define MTK_KPD_SEL_COLMASK(c)	GENMASK((c) + 9, 10)
>> @@ -31,6 +32,7 @@ struct mt6779_keypad {
>>   	struct clk *clk;
>>   	u32 n_rows;
>>   	u32 n_cols;
>> +	bool double_keys;
>>   	DECLARE_BITMAP(keymap_state, MTK_KPD_NUM_BITS);
>>   };
>>   
>> @@ -67,8 +69,13 @@ static irqreturn_t mt6779_keypad_irq_handler(int irq, void *dev_id)
>>   			continue;
>>   
>>   		key = bit_nr / 32 * 16 + bit_nr % 32;
>> -		row = key / 9;
>> -		col = key % 9;
>> +		if (keypad->double_keys) {
>> +			row = key / 13;
>> +			col = (key % 13) / 2;
>> +		} else {
>> +			row = key / 9;
>> +			col = key % 9;
>> +		}
>
> I don't fully like this if branch permanently evaluating true or false, as no
> runtime can actually change this result...
>
> In practice, it's fine, but I was wondering if anyone would disagree with the
> following proposal...
>
> struct mt6779_keypad {
> 	.......
> 	void (*calc_row_col)(unsigned int *row, unsigned int *col);
> };
>
> In mt6779_keypad_irq_handler:
>
> 	key = bit_nr / 32 * 16 + bit_nr % 32;
> 	keypad->calc_row_col(&row, &col);
>
> and below...
>
>>   
>>   		scancode = MATRIX_SCAN_CODE(row, col, row_shift);
>>   		/* 1: not pressed, 0: pressed */
>> @@ -150,6 +157,8 @@ static int mt6779_keypad_pdrv_probe(struct platform_device *pdev)
>>   
>>   	wakeup = device_property_read_bool(&pdev->dev, "wakeup-source");
>>   
>> +	keypad->double_keys = device_property_read_bool(&pdev->dev, "mediatek,double-keys");
>> +
>>   	dev_dbg(&pdev->dev, "n_row=%d n_col=%d debounce=%d\n",
>>   		keypad->n_rows, keypad->n_cols, debounce);
>>   
>> @@ -166,6 +175,10 @@ static int mt6779_keypad_pdrv_probe(struct platform_device *pdev)
>>   	regmap_write(keypad->regmap, MTK_KPD_DEBOUNCE,
>>   		     (debounce * (1 << 5)) & MTK_KPD_DEBOUNCE_MASK);
>>   
>> +	if (keypad->double_keys)
>
> 		keypad->calc_row_col = mt6779_keypad_calc_row_col_double_kp;
>
>> +		regmap_update_bits(keypad->regmap, MTK_KPD_SEL,
>> +				   MTK_KPD_SEL_DOUBLE_KP_MODE, MTK_KPD_SEL_DOUBLE_KP_MODE);
>> +
>
> 	} else {
> 		keypad->calc_row_col = mt6779_keypad_calc_row_col_single_kp;
> 	}
>
>>   	regmap_update_bits(keypad->regmap, MTK_KPD_SEL, MTK_KPD_SEL_ROW,
>>   			   MTK_KPD_SEL_ROWMASK(keypad->n_rows));
>>   	regmap_update_bits(keypad->regmap, MTK_KPD_SEL, MTK_KPD_SEL_COL,
>
> what do you think?

Hi Angelo,

Thank you for your detailed suggestion. I like it and since I have to
resend a v2 anyways, I will consider implementing it.
On the other hand, I'm a little reluctant because it means that I'll
have to remove Matthias's reviewed-by :(

>
> Cheers,
> Angelo