linux-kernel - Re: [PATCH v10 52/55] input: touchscreen: atmel_mxt_ts: Added sysfs entry for touchscreen status

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Message-ID: <63336277-8ed2-a097-a983-6e8ac48d776e@gmail.com>
Date:   Tue, 31 Mar 2020 18:08:49 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Jiada Wang <jiada_wang@...tor.com>, nick@...anahar.org,
        dmitry.torokhov@...il.com, jikos@...nel.org,
        benjamin.tissoires@...hat.com, bsz@...ihalf.com
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        erosca@...adit-jv.com, Andrew_Gabbasov@...tor.com
Subject: Re: [PATCH v10 52/55] input: touchscreen: atmel_mxt_ts: Added sysfs
 entry for touchscreen status

31.03.2020 13:50, Jiada Wang пишет:
...
> +static void mxt_watchdog_work(struct work_struct *work)
> +{
> +	struct mxt_data *data =
> +		container_of(work, struct mxt_data, watchdog_work.work);
> +	u16 info_buf;
> +	int ret;
> +
> +	if (data->suspended || data->in_bootloader ||
> +	    data->mxt_status.intp_triggered)
> +		goto sched_work;

Won't it become a problem if other thread puts device into suspended /
bootloader state in the same time?

> +	ret = __mxt_read_reg(data->client, 0, sizeof(info_buf), &info_buf);
> +
> +	if (ret) {
> +		data->mxt_status.error_count++;
> +		data->mxt_status.dev_status = false;
> +	} else {
> +		data->mxt_status.dev_status = true;
> +	}
> +
> +sched_work:
> +	schedule_delayed_work(&data->watchdog_work,
> +			      msecs_to_jiffies(MXT_WATCHDOG_TIMEOUT));
> +}
...

> @@ -4329,6 +4390,12 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  		msleep(MXT_RESET_TIME);
>  	}
>  
> +	if (debug_state) {
> +		INIT_DELAYED_WORK(&data->watchdog_work, mxt_watchdog_work);
> +		schedule_delayed_work(&data->watchdog_work,
> +				      msecs_to_jiffies(MXT_WATCHDOG_TIMEOUT));
> +	}
> +
>  	error = mxt_initialize(data);
>  	if (error)
>  		goto err_free_object;
> @@ -4343,6 +4410,8 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	return 0;
>  
>  err_free_object:
> +	if (debug_state)
> +		cancel_delayed_work_sync(&data->watchdog_work);
>  	mxt_free_input_device(data);
>  	mxt_free_object_table(data);
>  	if (data->reset_gpio) {
> @@ -4367,6 +4436,9 @@ static int mxt_remove(struct i2c_client *client)
>  	mxt_free_input_device(data);
>  	mxt_free_object_table(data);
>  
> +	if (debug_state)
> +		cancel_delayed_work_sync(&data->watchdog_work);

What will happen if debug_state was false during of mxt_probe() and then
the debug_state parameter was changed to true via sysfs?

I think the INIT_DELAYED_WORK() and cancel_delayed_work_sync() should be
invoked unconditionally.

>  	return 0;
>  }
>  
> @@ -4463,3 +4535,7 @@ module_i2c_driver(mxt_driver);
>  MODULE_AUTHOR("Joonyoung Shim <jy0922.shim@...sung.com>");
>  MODULE_DESCRIPTION("Atmel maXTouch Touchscreen driver");
>  MODULE_LICENSE("GPL");
> +
> +module_param(debug_state, bool, 0);
> +MODULE_PARM_DESC(debug_state, "Enable/Disable watchdog work to check device state (default="
> +		 __MODULE_STRING(MXT_DEBUG_STATE) ")");
> 

The "default=..." part of MODULE_PARM_DESC() probably isn't really
useful and could be omitted, don't you think so?