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Message-ID: <1eed6877-8868-6b29-b7c9-90986d230f36@collabora.com>
Date:   Thu, 21 Jul 2022 16:55:06 +0200
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Subject: Re: [PATCH v1 4/6] Input: mt6779-keypad - support double keys matrix
Content-Language: en-US
To:     Mattijs Korpershoek <mkorpershoek@baylibre.com>,
        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
References: <20220720-mt8183-keypad-v1-0-ef9fc29dbff4@baylibre.com>
 <20220720-mt8183-keypad-v1-4-ef9fc29dbff4@baylibre.com>
 <b2676b5c-14b3-2058-9fb8-d6d78cc5d29c@collabora.com>
 <87ilnqh632.fsf@baylibre.com>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <87ilnqh632.fsf@baylibre.com>
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Il 21/07/22 16:51, Mattijs Korpershoek ha scritto:
> On Thu, Jul 21, 2022 at 10:34, AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.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@baylibre.com>
>>> Reviewed-by: Matthias Brugger <matthias.bgg@gmail.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 :(
> 

Yes, you will have to. In that case:

Matthias, any considerations about this idea? :)))

>>
>> Cheers,
>> Angelo