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

From: Gabriele Mazzotta
Date: Tue May 24 2016 - 16:53:34 EST


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@xxxxxxxxx>
---
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