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

Rafael J. Wysocki
2016-07-23T12:32:12Z

On Friday, July 22, 2016 02:24:42 PM Lv Zheng wrote:
> 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.

Can you please provide a high-level description of the new mechanism here?

>
> Signed-off-by: Lv Zheng <lv.zheng@intel.com>
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: Benjamin Tissoires <benjamin.tissoires@gmail.com>
> Cc: Bastien Nocera: <hadess@hadess.net>
> Cc: linux-input@vger.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);

Is it really necessary to use jiffies here?

> + if (time_after(jiffies, sw_tout) &&
> + (button->sw_last_state == !!state)) {

The inner parens are not necessary.

And why not just 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;
>

Thanks,
Rafael