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

[Wang, Jiada]

Hi Dmitry

Thanks for your comments

On 2020/04/01 0:08, Dmitry Osipenko wrote:
> 31.03.2020 13:50, Jiada Wang ÐÐÑÐÑ:
> ...
> > +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?
right, I will use mutex lock to prevent such case.
also I think data->mxt_status.intp_triggered isn't necessary,
when lock is used.

> > +	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?

module_param debug_state is added with permission 0,
so it's value won't change during driver operation
> 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@xxxxxxxxxxx>");
> >   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?
since debug_state can't be updated via sysfs, so I think add it's 
default in MODULE_PARM_DESC() is useful? what's your opinion?

Thanks,
Jiada