Re: [PATCH v11 33/56] Input: atmel_mxt_ts - delay enabling IRQ when not using regulators

[Dmitry Osipenko]

08.05.2020 08:56, Jiada Wang ÐÐÑÐÑ:
> The path of enabling the IRQ in the probe function is not safe in level
> triggered operation, if it was already powered up and there is a message
> waiting on the device (eg finger down) because the object table has not yet
> been read. This forces the ISR into a hard loop.
> 
> Delay enabling the interrupt until it is first needed, by set flag
> IRQ_NOAUTOEN.
> 
> Signed-off-by: Jiada Wang <jiada_wang@xxxxxxxxxx>
> CC: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
>  drivers/input/touchscreen/atmel_mxt_ts.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 7c9a738e633a..ab4eceac8fe7 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -3822,6 +3822,7 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  		return error;
>  	}
>  
> +	irq_set_status_flags(client->irq, IRQ_NOAUTOEN);
>  	error = devm_request_threaded_irq(&client->dev, client->irq,
>  					  NULL, mxt_interrupt, IRQF_ONESHOT,
>  					  client->name, data);
> @@ -3831,17 +3832,19 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	}
>  
>  	if (data->suspend_mode == MXT_SUSPEND_REGULATOR) {
> +		enable_irq(data->irq);

Hello Jiada,

This change contradicts to the commit's message since enabling IRQ until
hardware has been fully powered-on and reset is not allowed.

>  		error = mxt_probe_regulators(data);
>  		if (error)
>  			return error;
> +
> +		disable_irq(data->irq);
>  	} else if (data->reset_gpio) {
>  		msleep(MXT_RESET_GPIO_TIME);
>  		gpiod_set_value(data->reset_gpio, 1);
>  		msleep(MXT_RESET_INVALID_CHG);
>  	}
>  
> -	disable_irq(data->irq);
> -
>  	error = mxt_initialize(data);
>  	if (error)
>  		return error;
> 

Secondly, I gave a try to this version of the series and unfortunately
it doesn't work at all:

[  125.928709] INFO: task systemd-udevd:184 blocked for more than 61
seconds.
[  125.929130]       Not tainted
5.7.0-rc4-next-20200508-00189-g0fe7f91d4a66-dirty #2206
[  125.929474] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[  125.929900] systemd-udevd   D    0   184    173 0x00000080
[  125.929921] [<c098b995>] (__schedule) from [<c098bdc1>]
(schedule+0x65/0xc0)
[  125.929965] [<c098bdc1>] (schedule) from [<c0166ce3>]
(synchronize_irq+0x5b/0x7c)
[  125.930001] [<c0166ce3>] (synchronize_irq) from [<c067e0f9>]
(mxt_stop+0x51/0xe0)
[  125.930016] [<c067e0f9>] (mxt_stop) from [<c067e1d3>]
(mxt_input_close+0x13/0x34)
[  125.930042] [<c067e1d3>] (mxt_input_close) from [<c0664b19>]
(input_close_device+0x3d/0x5c)
[  125.930063] [<c0664b19>] (input_close_device) from [<c066b9df>]
(evdev_release+0xa7/0xbc)
[  125.930088] [<c066b9df>] (evdev_release) from [<c025a871>]
(__fput+0x91/0x198)
[  125.930121] [<c025a871>] (__fput) from [<c0136efb>]
(task_work_run+0x73/0x90)
[  125.930138] [<c0136efb>] (task_work_run) from [<c0108fa9>]
(do_work_pending+0x381/0x430)
[  125.930149] [<c0108fa9>] (do_work_pending) from [<c01000d1>]
(slow_work_pending+0x9/0x18)
[  125.930153] Exception stack(0xedd0ffb0 to 0xedd0fff8)

Please test everything properly and fix it in the next version.

BTW, it won't hurt to apply a spell-checker to the commit messages to
fix small typos.