Re: [WIP PATCH 3/4] ACPI: button: Let input filter out the LID events

[Benjamin Tissoires]

On Jun 05 2017 or thereabouts, Zheng, Lv wrote:
> Hi, Benjamin
> 
> > From: Benjamin Tissoires [mailto:benjamin.tissoires@xxxxxxxxxx]
> > Subject: [WIP PATCH 3/4] ACPI: button: Let input filter out the LID events
> > 
> > The input stack already filters out the LID events. So instead of
> > filtering them out at the source, we can hook up after the input
> > processing and propagate the lid switch events when the input stack
> > tells us to.
> > 
> > An other benefit is that if userspace (think libinput) "fixes" the lid
> > switch state by some heuristics, this new state is forwarded to the
> > listeners in the kernel.
> 
> See my comments to PATCH 4.
> IMO, it sounds better that
> 1. ACPI lid works as a driver of SW_LID, and
> 2. i915 registers notification (the only user) via input layer.
> So it looks i915 rather than button driver should call input_register_handler().
> And input layer may help to provide a simplified interface for drivers to register key notifications.

Sounds good.

Dmitry, would a simplified API for other drivers to listen to input
events be something you would agree on?

Cheers,
Benjamin

> 
> Thanks and best regards
> Lv
> 
> > 
> > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> > ---
> >  drivers/acpi/button.c | 156 ++++++++++++++++++++++++++++++++++++++++++++------
> >  1 file changed, 139 insertions(+), 17 deletions(-)
> > 
> > diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> > index 9ad7604..03e5981 100644
> > --- a/drivers/acpi/button.c
> > +++ b/drivers/acpi/button.c
> > @@ -109,8 +109,6 @@ struct acpi_button {
> >  	struct input_dev *input;
> >  	char phys[32];			/* for input device */
> >  	unsigned long pushed;
> > -	int last_state;
> > -	ktime_t last_time;
> >  	bool suspended;
> >  };
> > 
> > @@ -184,7 +182,6 @@ static int acpi_lid_evaluate_state(struct acpi_device *device)
> >  static int acpi_lid_notify_state(struct acpi_device *device, int state)
> >  {
> >  	struct acpi_button *button = acpi_driver_data(device);
> > -	int ret;
> > 
> >  	/* button_input_lock must be held */
> > 
> > @@ -205,20 +202,129 @@ static int acpi_lid_notify_state(struct acpi_device *device, int state)
> >  	if (state)
> >  		pm_wakeup_hard_event(&device->dev);
> > 
> > -	ret = blocking_notifier_call_chain(&acpi_lid_notifier, state, device);
> > -	if (ret == NOTIFY_DONE)
> > -		ret = blocking_notifier_call_chain(&acpi_lid_notifier, state,
> > -						   device);
> > -	if (ret == NOTIFY_DONE || ret == NOTIFY_OK) {
> > -		/*
> > -		 * It is also regarded as success if the notifier_chain
> > -		 * returns NOTIFY_OK or NOTIFY_DONE.
> > -		 */
> > -		ret = 0;
> > +	return 0;
> > +}
> > +
> > +/*
> > + * Pass incoming event to all connected clients.
> > + */
> > +static void acpi_button_lid_events(struct input_handle *handle,
> > +				   const struct input_value *vals,
> > +				   unsigned int count)
> > +{
> > +	const struct input_value *v;
> > +	int state = -1;
> > +	int ret;
> > +
> > +	for (v = vals; v != vals + count; v++) {
> > +		switch (v->type) {
> > +		case EV_SYN:
> > +			if (v->code == SYN_REPORT && state >= 0) {
> > +				ret = blocking_notifier_call_chain(&acpi_lid_notifier,
> > +								state,
> > +								lid_device);
> > +				if (ret == NOTIFY_DONE)
> > +					ret = blocking_notifier_call_chain(&acpi_lid_notifier,
> > +								state,
> > +								lid_device);
> > +				if (ret == NOTIFY_DONE || ret == NOTIFY_OK) {
> > +					/*
> > +					 * It is also regarded as success if
> > +					 * the notifier_chain returns NOTIFY_OK
> > +					 * or NOTIFY_DONE.
> > +					 */
> > +					ret = 0;
> > +				}
> > +			}
> > +			break;
> > +		case EV_SW:
> > +			if (v->code == SW_LID)
> > +				state = !v->value;
> > +			break;
> > +		}
> >  	}
> > -	return ret;
> >  }
> > 
> > +static int acpi_button_lid_connect(struct input_handler *handler,
> > +				   struct input_dev *dev,
> > +				   const struct input_device_id *id)
> > +{
> > +	struct input_handle *handle;
> > +	int error;
> > +
> > +	handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
> > +	if (!handle)
> > +		return -ENOMEM;
> > +
> > +	handle->dev = dev;
> > +	handle->handler = handler;
> > +	handle->name = "acpi-button-lid";
> > +
> > +	error = input_register_handle(handle);
> > +	if (error) {
> > +		dev_err(&lid_device->dev, "Error installing input handle\n");
> > +		goto err_free;
> > +	}
> > +
> > +	error = input_open_device(handle);
> > +	if (error) {
> > +		dev_err(&lid_device->dev, "Failed to open input device\n");
> > +		goto err_unregister;
> > +	}
> > +
> > +	return 0;
> > +
> > + err_unregister:
> > +	input_unregister_handle(handle);
> > + err_free:
> > +	kfree(handle);
> > +	return error;
> > +}
> > +
> > +static void acpi_button_lid_disconnect(struct input_handle *handle)
> > +{
> > +	input_close_device(handle);
> > +	input_unregister_handle(handle);
> > +	kfree(handle);
> > +}
> > +
> > +bool acpi_button_lid_match(struct input_handler *handler,
> > +			   struct input_dev *dev)
> > +{
> > +	struct acpi_button *button;
> > +
> > +	if (!lid_device)
> > +		return false;
> > +
> > +	button = acpi_driver_data(lid_device);
> > +
> > +	if (dev != button->input)
> > +		return false;
> > +
> > +	return true;
> > +}
> > +
> > +static const struct input_device_id acpi_button_lid_ids[] = {
> > +	{
> > +		.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
> > +		.evbit = { BIT_MASK(EV_SW) },
> > +		.swbit = { BIT_MASK(SW_LID) },
> > +	},
> > +	{ },
> > +};
> > +
> > +MODULE_DEVICE_TABLE(input, acpi_button_lid_ids);
> > +
> > +static struct input_handler acpi_button_lid_handler = {
> > +	.match		= acpi_button_lid_match,
> > +	.connect	= acpi_button_lid_connect,
> > +	.disconnect	= acpi_button_lid_disconnect,
> > +	.events		= acpi_button_lid_events,
> > +	.name		= "acpi-lid-callchain",
> > +	.id_table	= acpi_button_lid_ids,
> > +};
> > +
> > +
> >  static int acpi_button_state_seq_show(struct seq_file *seq, void *offset)
> >  {
> >  	struct acpi_device *device = seq->private;
> > @@ -581,8 +687,6 @@ static int acpi_button_add(struct acpi_device *device)
> >  		strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
> >  		sprintf(class, "%s/%s",
> >  			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
> > -		button->last_state = !!acpi_lid_evaluate_state(device);
> > -		button->last_time = ktime_get();
> >  	} else {
> >  		printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
> >  		error = -ENODEV;
> > @@ -674,4 +778,22 @@ module_param_call(lid_init_state,
> >  		  NULL, 0644);
> >  MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
> > 
> > -module_acpi_driver(acpi_button_driver);
> > +static int __init acpi_button_init(void)
> > +{
> > +	int error;
> > +
> > +	error = input_register_handler(&acpi_button_lid_handler);
> > +	if (error)
> > +		return error;
> > +
> > +	return acpi_bus_register_driver(&acpi_button_driver);
> > +}
> > +
> > +static void __exit acpi_button_exit(void)
> > +{
> > +	acpi_bus_unregister_driver(&acpi_button_driver);
> > +	input_unregister_handler(&acpi_button_lid_handler);
> > +}
> > +
> > +module_init(acpi_button_init);
> > +module_exit(acpi_button_exit);
> > --
> > 2.9.4
>