drm/amdgpu: Suppress keypresses from ACPI_VIDEO events

Currently we return NOTIFY_DONE for any event which we don't think is
ours. However, many laptops will send more then just an ATIF event and
will also send an ACPI_VIDEO_NOTIFY_PROBE event as well. Since we don't
check for this, we return NOTIFY_DONE which causes a keypress for the
ACPI event to be propogated to userspace. This is the equivalent of
someone pressing the display key on a laptop every time there's a
hotplug event.

So, check for ACPI_VIDEO_NOTIFY_PROBE events and suppress keypresses
from them.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c

@@ -359,7 +359,9 @@ static int amdgpu_atif_get_sbios_requests(struct amdgpu_atif *atif,
  *
  * Checks the acpi event and if it matches an atif event,
  * handles it.
- * Returns NOTIFY code
+ *
+ * Returns:
+ * NOTIFY_BAD or NOTIFY_DONE, depending on the event.
  */
 static int amdgpu_atif_handler(struct amdgpu_device *adev,
 			       struct acpi_bus_event *event)
@@ -373,11 +375,16 @@ static int amdgpu_atif_handler(struct amdgpu_device *adev,
 	if (strcmp(event->device_class, ACPI_VIDEO_CLASS) != 0)
 		return NOTIFY_DONE;
 
+	/* Is this actually our event? */
 	if (!atif ||
 	    !atif->notification_cfg.enabled ||
-	    event->type != atif->notification_cfg.command_code)
-		/* Not our event */
+	    event->type != atif->notification_cfg.command_code) {
+		/* These events will generate keypresses otherwise */
+		if (event->type == ACPI_VIDEO_NOTIFY_PROBE)
+			return NOTIFY_BAD;
+		else
 			return NOTIFY_DONE;
+	}
 
 	if (atif->functions.sbios_requests) {
 		struct atif_sbios_requests req;
@@ -386,7 +393,7 @@ static int amdgpu_atif_handler(struct amdgpu_device *adev,
 		count = amdgpu_atif_get_sbios_requests(atif, &req);
 
 		if (count <= 0)
-			return NOTIFY_DONE;
+			return NOTIFY_BAD;
 
 		DRM_DEBUG_DRIVER("ATIF: %d pending SBIOS requests\n", count);