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Subject: Re: [PATCH v9 52/55] input: touchscreen: atmel_mxt_ts: Added sysfs
 entry for touchscreen status
To:     Jiada Wang <jiada_wang@mentor.com>, nick@shmanahar.org,
        dmitry.torokhov@gmail.com, jikos@kernel.org,
        benjamin.tissoires@redhat.com, bsz@semihalf.com,
        rydberg@bitmath.org
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        erosca@de.adit-jv.com, Andrew_Gabbasov@mentor.com
References: <20200325133334.19346-1-jiada_wang@mentor.com>
 <20200325133334.19346-53-jiada_wang@mentor.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <4aeda6f1-25d8-9437-5cd0-560e43dbe081@gmail.com>
Date:   Wed, 25 Mar 2020 22:35:22 +0300
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25.03.2020 16:33, Jiada Wang пишет:
> From: Naveen Chakka <Naveen.Chakka@in.bosch.com>
> 
> To know the current communication status of the touch controller during
> runtime, sysfs interface is added
> 
> sysfs interface: /sys/class/i2c-dev/i2c-*/device/*/touch_dev_stat
> Executing the above sysfs interface provides two output values
> 
> 1)Status of the touch device
> 	value 0 represents device is inactive
> 	value 1 represents device is active
> 2)Error counter
> 	value represents the number of times device in inactive since last read

...
>  /* Each client has this additional data */
>  struct mxt_data {
>  	struct i2c_client *client;
> @@ -372,6 +380,9 @@ struct mxt_data {
>  	const char *pcfg_name;
>  	const char *input_name;
>  	struct mxt_flash *flash;

> +	struct work_struct watchdog_work;
> +	struct timer_list watchdog_timer;

This should be replaced with a delayed_work.

> +	struct mxt_statusinfo mxt_status;
>  
>  	/* Cached parameters from object table */
>  	u16 T5_address;

...
> +static void mxt_watchdog_work(struct work_struct *work)
> +{
> +	struct mxt_data *data =
> +		container_of(work, struct mxt_data, watchdog_work);
> +	u16 info_buf;
> +	int ret = 0;
> +	u8 size = 2;

> +	if (data->suspended || data->in_bootloader)
> +		return;
> +
> +	ret = __mxt_read_reg(data->client, 0, size, &info_buf);

Looks like this need to be protected with a lock to not race with the
suspending / bootloader states.

> +	if (ret) {
> +		data->mxt_status.error_count++;
> +		data->mxt_status.dev_status = false;
> +	} else {
> +		data->mxt_status.dev_status = true;
> +	}
> +}

...> @@ -4329,6 +4414,13 @@ static int mxt_probe(struct i2c_client
*client, const struct i2c_device_id *id)
>  		msleep(MXT_RESET_TIME);
>  	}
>  
> +	INIT_WORK(&data->watchdog_work, mxt_watchdog_work);
> +
> +	/* setup watchdog timer */
> +	timer_setup(&data->watchdog_timer, mxt_watchdog_timer, 0);
> +
> +	mxt_start_wd_timer(data);

I'd expect it to be optional and opt-in by either using #ifdef
TOUCHSCREEN_ATMEL_MXT_DEBUG or having a new debugfs option to explicitly
enable the "watchdog".