linux-kernel - RE: [PATCH v5 1/3] ACPI / button: Add missing event to keep SW_LID running without additional event loss

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Message-ID: <1AE640813FDE7649BE1B193DEA596E883BC05E41@SHSMSX101.ccr.corp.intel.com>
Date:	Fri, 22 Jul 2016 10:26:24 +0000
From:	"Zheng, Lv" <lv.zheng@...el.com>
To:	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Brown, Len" <len.brown@...el.com>
CC:	Lv Zheng <zetalog@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Benjamin Tissoires <benjamin.tissoires@...il.com>,
	"Bastien Nocera:" <hadess@...ess.net>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>
Subject: RE: [PATCH v5 1/3] ACPI / button: Add missing event to keep SW_LID
 running without additional event loss

Hi, Dmitry

I'm considering what the future should be.

What if we drop PATCH 02, stop introducing KEY_LID_XXX events.
And switch ACPI button driver to lid_init_state=ignore.
So that whatever the initial state is close or open, no events will be sent to the userspace.
In the meanwhile, userspace tunes its behavior.
With PATCH 01, 2nd close can arrive to userspace, so that can be tuned to:
1. User space stops asking kernel to send open notification.
2. And only acts against "close" notification.

Thanks and best regards
-Lv

> From: Zheng, Lv
> Subject: [PATCH v5 1/3] ACPI / button: Add missing event to keep SW_LID
> running without additional event loss
> 
> There are several possibilities that a lid event can be lost. For example,
> EC event queue full, or the resume order of the underlying drivers.
> 
> When the event loss happens, new event may also be lost due to the type
> of
> the SW_LID (switch event). The 2nd loss is what we want to avoid.
> 
> This patch adds a mechanism to insert lid events as a compensation for
> the
> switch event nature of the lid events in order to avoid the 2nd loss.
> 
> Signed-off-by: Lv Zheng <lv.zheng@...el.com>
> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> Cc: Benjamin Tissoires <benjamin.tissoires@...il.com>
> Cc: Bastien Nocera: <hadess@...ess.net>
> Cc: linux-input@...r.kernel.org
> ---
>  drivers/acpi/button.c |   21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> index 148f4e5..41fd21d 100644
> --- a/drivers/acpi/button.c
> +++ b/drivers/acpi/button.c
> @@ -104,6 +104,8 @@ struct acpi_button {
>  	struct input_dev *input;
>  	char phys[32];			/* for input device */
>  	unsigned long pushed;
> +	int sw_last_state;
> +	unsigned long sw_last_time;
>  	bool suspended;
>  };
> 
> @@ -111,6 +113,10 @@ static
> BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
>  static struct acpi_device *lid_device;
>  static u8 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
> 
> +static unsigned long lid_report_interval __read_mostly = 500;
> +module_param(lid_report_interval, ulong, 0644);
> +MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key
> events");
> +
>  /* --------------------------------------------------------------------------
>                                FS Interface (/proc)
>     -------------------------------------------------------------------------- */
> @@ -133,11 +139,22 @@ 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);
> +	unsigned long sw_tout;
>  	int ret;
> 
> -	/* input layer checks if event is redundant */
> +	/* Send the switch event */
> +	sw_tout = button->sw_last_time +
> +		  msecs_to_jiffies(lid_report_interval);
> +	if (time_after(jiffies, sw_tout) &&
> +	    (button->sw_last_state == !!state)) {
> +		/* Send the complement switch event */
> +		input_report_switch(button->input, SW_LID, state);
> +		input_sync(button->input);
> +	}
>  	input_report_switch(button->input, SW_LID, !state);
>  	input_sync(button->input);
> +	button->sw_last_state = !!state;
> +	button->sw_last_time = jiffies;
> 
>  	if (state)
>  		pm_wakeup_event(&device->dev, 0);
> @@ -407,6 +424,8 @@ 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->sw_last_state = !!acpi_lid_evaluate_state(device);
> +		button->sw_last_time = jiffies;
>  	} else {
>  		printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
>  		error = -ENODEV;
> --
> 1.7.10