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

[Dmitry Osipenko]

01.04.2020 15:51, Wang, Jiada ÐÐÑÐÑ:
> 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)
>>> +{
>>> +ÂÂÂ struct mxt_data *data =
>>> +ÂÂÂÂÂÂÂ container_of(work, struct mxt_data, watchdog_work.work);
>>> +ÂÂÂ u16 info_buf;
>>> +ÂÂÂ int ret;
>>> +
>>> +ÂÂÂ if (data->suspended || data->in_bootloader ||
>>> +ÂÂÂÂÂÂÂ data->mxt_status.intp_triggered)
>>> +ÂÂÂÂÂÂÂ 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.
> 
>>> +ÂÂÂ ret = __mxt_read_reg(data->client, 0, sizeof(info_buf), &info_buf);
>>> +
>>> +ÂÂÂ if (ret) {
>>> +ÂÂÂÂÂÂÂ data->mxt_status.error_count++;
>>> +ÂÂÂÂÂÂÂ data->mxt_status.dev_status = false;
>>> +ÂÂÂ } else {
>>> +ÂÂÂÂÂÂÂ data->mxt_status.dev_status = true;
>>> +ÂÂÂ }
>>> +
>>> +sched_work:
>>> +ÂÂÂ schedule_delayed_work(&data->watchdog_work,
>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ msecs_to_jiffies(MXT_WATCHDOG_TIMEOUT));
>>> +}
>> ...
>>
>>> @@ -4329,6 +4390,12 @@ static int mxt_probe(struct i2c_client
>>> *client, const struct i2c_device_id *id)
>>> ÂÂÂÂÂÂÂÂÂ msleep(MXT_RESET_TIME);
>>> ÂÂÂÂÂ }
>>> Â +ÂÂÂ if (debug_state) {
>>> +ÂÂÂÂÂÂÂ INIT_DELAYED_WORK(&data->watchdog_work, mxt_watchdog_work);
>>> +ÂÂÂÂÂÂÂ schedule_delayed_work(&data->watchdog_work,
>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ msecs_to_jiffies(MXT_WATCHDOG_TIMEOUT));
>>> +ÂÂÂ }
>>> +
>>> ÂÂÂÂÂ error = mxt_initialize(data);
>>> ÂÂÂÂÂ if (error)
>>> ÂÂÂÂÂÂÂÂÂ goto err_free_object;
>>> @@ -4343,6 +4410,8 @@ static int mxt_probe(struct i2c_client *client,
>>> const struct i2c_device_id *id)
>>> ÂÂÂÂÂ return 0;
>>> Â Â err_free_object:
>>> +ÂÂÂ if (debug_state)
>>> +ÂÂÂÂÂÂÂ cancel_delayed_work_sync(&data->watchdog_work);
>>> ÂÂÂÂÂ mxt_free_input_device(data);
>>> ÂÂÂÂÂ mxt_free_object_table(data);
>>> ÂÂÂÂÂ if (data->reset_gpio) {
>>> @@ -4367,6 +4436,9 @@ static int mxt_remove(struct i2c_client *client)
>>> ÂÂÂÂÂ mxt_free_input_device(data);
>>> ÂÂÂÂÂ mxt_free_object_table(data);
>>> Â +ÂÂÂ if (debug_state)
>>> +ÂÂÂÂÂÂÂ 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

Thank you for the clarification, I didn't realize that setting
permission to 0 hides the parameter completely in sysfs.

>> I think the INIT_DELAYED_WORK() and cancel_delayed_work_sync() should be
>> invoked unconditionally.
>>
>>> ÂÂÂÂÂ return 0;
>>> Â }
>>> Â @@ -4463,3 +4535,7 @@ module_i2c_driver(mxt_driver);
>>> Â MODULE_AUTHOR("Joonyoung Shim <jy0922.shim@xxxxxxxxxxx>");
>>> Â MODULE_DESCRIPTION("Atmel maXTouch Touchscreen driver");
>>> Â MODULE_LICENSE("GPL");
>>> +
>>> +module_param(debug_state, bool, 0);
>>> +MODULE_PARM_DESC(debug_state, "Enable/Disable watchdog work to check
>>> device state (default="
>>> +ÂÂÂÂÂÂÂÂ __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?

If you want to keep the "default" kept in the description, then perhaps
a simple "default=false" should be enough because nothing would be able
to change it to true.