linux-kernel - Re: [PATCH v4] dell-rbtn: Ignore ACPI notifications if device is suspended

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Date:	Wed, 25 May 2016 13:28:47 -0700
From:	Darren Hart <dvhart@...radead.org>
To:	Gabriele Mazzotta <gabriele.mzt@...il.com>,
	Pali Rohár <pali.rohar@...il.com>
Cc:	arvidjaar@...il.com, rjw@...ysocki.net, Jared_Dominguez@...l.com,
	platform-driver-x86@...r.kernel.org, alex.hung@...onical.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] dell-rbtn: Ignore ACPI notifications if device is
 suspended

On Tue, May 24, 2016 at 10:53:08PM +0200, Gabriele Mazzotta wrote:
> Some BIOSes unconditionally send an ACPI notification to RBTN when the
> system is resuming from suspend. This makes dell-rbtn send an input
> event to userspace as if a function key was pressed. Prevent this by
> ignoring all the notifications received while the device is suspended.
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=106031
> Signed-off-by: Gabriele Mazzotta <gabriele.mzt@...il.com>

Gabriele, please include all the maintainers on Cc (Pali was missing).

Pali, can I have your Reviewed-by?

> ---
>  drivers/platform/x86/dell-rbtn.c | 56 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 56 insertions(+)
> 
> diff --git a/drivers/platform/x86/dell-rbtn.c b/drivers/platform/x86/dell-rbtn.c
> index 331d63c..dd22fb9 100644
> --- a/drivers/platform/x86/dell-rbtn.c
> +++ b/drivers/platform/x86/dell-rbtn.c
> @@ -28,6 +28,7 @@ struct rbtn_data {
>  	enum rbtn_type type;
>  	struct rfkill *rfkill;
>  	struct input_dev *input_dev;
> +	bool suspended;
>  };
>  
>  
> @@ -235,9 +236,55 @@ static const struct acpi_device_id rbtn_ids[] = {
>  	{ "", 0 },
>  };
>  
> +#ifdef CONFIG_PM_SLEEP
> +static void ACPI_SYSTEM_XFACE rbtn_clear_suspended_flag(void *context)
> +{
> +	struct rbtn_data *rbtn_data = context;
> +
> +	rbtn_data->suspended = false;
> +}
> +
> +static int rbtn_suspend(struct device *dev)
> +{
> +	struct acpi_device *device = to_acpi_device(dev);
> +	struct rbtn_data *rbtn_data = acpi_driver_data(device);
> +
> +	rbtn_data->suspended = true;
> +
> +	return 0;
> +}
> +
> +static int rbtn_resume(struct device *dev)
> +{
> +	struct acpi_device *device = to_acpi_device(dev);
> +	struct rbtn_data *rbtn_data = acpi_driver_data(device);
> +	acpi_status status;
> +
> +	/*
> +	 * Upon resume, some BIOSes send an ACPI notification thet triggers
> +	 * an unwanted input event. In order to ignore it, we use a flag
> +	 * that we set at suspend and clear once we have received the extra
> +	 * ACPI notification. Since ACPI notifications are delivered
> +	 * asynchronously to drivers, we clear the flag from the workqueue
> +	 * used to deliver the notifications. This should be enough
> +	 * to have the flag cleared only after we received the extra
> +	 * notification, if any.
> +	 */
> +	status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> +			 rbtn_clear_suspended_flag, rbtn_data);
> +	if (ACPI_FAILURE(status))
> +		rbtn_clear_suspended_flag(rbtn_data);
> +
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
> +
>  static struct acpi_driver rbtn_driver = {
>  	.name = "dell-rbtn",
>  	.ids = rbtn_ids,
> +	.drv.pm = &rbtn_pm_ops,
>  	.ops = {
>  		.add = rbtn_add,
>  		.remove = rbtn_remove,
> @@ -399,6 +446,15 @@ static void rbtn_notify(struct acpi_device *device, u32 event)
>  {
>  	struct rbtn_data *rbtn_data = device->driver_data;
>  
> +	/*
> +	 * Some BIOSes send a notification at resume.
> +	 * Ignore it to prevent unwanted input events.
> +	 */
> +	if (rbtn_data->suspended) {
> +		dev_dbg(&device->dev, "ACPI notification ignored\n");
> +		return;
> +	}
> +
>  	if (event != 0x80) {
>  		dev_info(&device->dev, "Received unknown event (0x%x)\n",
>  			 event);
> -- 
> 2.8.1
> 
> 

-- 
Darren Hart
Intel Open Source Technology Center