linux-kernel - Re: [PATCH 5/5] Input: tca6416-keypad - switch to using input core's polling features

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Message-Id: <2KN6Z0RZYGDKU.2GGSSC8MYU6GX@homearch.localdomain>
Date:   Tue, 25 Jul 2023 21:43:12 +0200
From:   "Silvan Jegen" <s.jegen@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-input@...r.kernel.org, Yangtao Li <frank.li@...o.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] Input: tca6416-keypad - switch to using input core's
 polling features

Hi

Just one question below.

Dmitry Torokhov <dmitry.torokhov@...il.com> wrote:
> Instead of rolling custom polling implementation use input core
> facilities.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> ---
>  drivers/input/keyboard/tca6416-keypad.c | 46 ++++++++++---------------
>  1 file changed, 19 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/input/keyboard/tca6416-keypad.c b/drivers/input/keyboard/tca6416-keypad.c
> index ff665319791e..ebc8b9561266 100644
> --- a/drivers/input/keyboard/tca6416-keypad.c
> +++ b/drivers/input/keyboard/tca6416-keypad.c
> @@ -24,6 +24,8 @@
>  #define TCA6416_INVERT         2
>  #define TCA6416_DIRECTION      3
>  
> +#define TCA6416_POLL_INTERVAL	100 /* msec */
> +
>  static const struct i2c_device_id tca6416_id[] = {
>  	{ "tca6416-keys", 16, },
>  	{ "tca6408-keys", 8, },
> @@ -43,7 +45,6 @@ struct tca6416_keypad_chip {
>  
>  	struct i2c_client *client;
>  	struct input_dev *input;
> -	struct delayed_work dwork;
>  	int io_size;
>  	int irqnum;
>  	u16 pinmask;
> @@ -85,9 +86,9 @@ static int tca6416_read_reg(struct tca6416_keypad_chip *chip, int reg, u16 *val)
>  	return 0;
>  }
>  
> -static void tca6416_keys_scan(struct tca6416_keypad_chip *chip)
> +static void tca6416_keys_scan(struct input_dev *input)
>  {
> -	struct input_dev *input = chip->input;
> +	struct tca6416_keypad_chip *chip = input_get_drvdata(input);
>  	u16 reg_val, val;
>  	int error, i, pin_index;
>  
> @@ -122,33 +123,20 @@ static void tca6416_keys_scan(struct tca6416_keypad_chip *chip)
>   */
>  static irqreturn_t tca6416_keys_isr(int irq, void *dev_id)
>  {
> -	struct tca6416_keypad_chip *chip = dev_id;
> -
> -	tca6416_keys_scan(chip);
> +	tca6416_keys_scan(dev_id);
>  
>  	return IRQ_HANDLED;
>  }
>  
> -static void tca6416_keys_work_func(struct work_struct *work)
> -{
> -	struct tca6416_keypad_chip *chip =
> -		container_of(work, struct tca6416_keypad_chip, dwork.work);
> -
> -	tca6416_keys_scan(chip);
> -	schedule_delayed_work(&chip->dwork, msecs_to_jiffies(100));
> -}
> -
>  static int tca6416_keys_open(struct input_dev *dev)
>  {
>  	struct tca6416_keypad_chip *chip = input_get_drvdata(dev);
>  
> -	/* Get initial device state in case it has switches */
> -	tca6416_keys_scan(chip);
> -
> -	if (chip->use_polling)
> -		schedule_delayed_work(&chip->dwork, msecs_to_jiffies(100));
> -	else
> +	if (!chip->use_polling) {
> +		/* Get initial device state in case it has switches */
> +		tca6416_keys_scan(dev);
>  		enable_irq(chip->client->irq);
> +	}
>  
>  	return 0;
>  }
> @@ -157,9 +145,7 @@ static void tca6416_keys_close(struct input_dev *dev)
>  {
>  	struct tca6416_keypad_chip *chip = input_get_drvdata(dev);
>  
> -	if (chip->use_polling)
> -		cancel_delayed_work_sync(&chip->dwork);
> -	else
> +	if (!chip->use_polling)
>  		disable_irq(chip->client->irq);
>  }
>  
> @@ -232,8 +218,6 @@ static int tca6416_keypad_probe(struct i2c_client *client)
>  	chip->pinmask = pdata->pinmask;
>  	chip->use_polling = pdata->use_polling;
>  
> -	INIT_DELAYED_WORK(&chip->dwork, tca6416_keys_work_func);
> -
>  	input->phys = "tca6416-keys/input0";
>  	input->name = client->name;
>  
> @@ -268,12 +252,20 @@ static int tca6416_keypad_probe(struct i2c_client *client)
>  		return error;
>  
>  	if (!chip->use_polling) {

Sorry for my ignorant question but it seems counterituitive that we set
up polling when chip->use_polling is false. Is this intended?

Cheers,
Silvan

> +		error = input_setup_polling(input, tca6416_keys_scan);
> +		if (error) {
> +			dev_err(&client->dev, "Failed to setup polling\n");
> +			return error;
> +		}
> +
> +		input_set_poll_interval(input, TCA6416_POLL_INTERVAL);
> +	} else {
>  		error = devm_request_threaded_irq(&client->dev, client->irq,
>  						  NULL, tca6416_keys_isr,
>  						  IRQF_TRIGGER_FALLING |
>  							IRQF_ONESHOT |
>  							IRQF_NO_AUTOEN,
> -						  "tca6416-keypad", chip);
> +						  "tca6416-keypad", input);
>  		if (error) {
>  			dev_dbg(&client->dev,
>  				"Unable to claim irq %d; error %d\n",