commit 90b066b15eda028ed44299f01236f8576dd8551d
author Hans de Goede <hdegoede@redhat.com> Tue Dec 22 19:09:48 2015 +0100
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> Fri Jan 01 03:14:51 2016 +0100
tree 31f5d270508137734424f5f1474d35bc86976df5
parent 74bf8efb5fa6e958d2d7c7917b8bb672085ec0c6

ACPI / video: Add a acpi_video_handles_brightness_key_presses() helper

Several drivers want to know if the acpi-video is generating key-presses
for brightness change hotkeys to avoid sending double key-events to
userspace for these. Currently these driver use this construct for this:

	if (acpi_video_get_backlight_type() == acpi_backlight_vendor)
		report_brightness_key_event();

This indirect way of detecting if acpi-video is active does not make the
code easier to understand, and in some cases it is wrong because just
because the preferred type != vendor does not mean that acpi-video is
actually listening for brightness events, e.g. there may be no acpi-video
bus on the system at all.

This commit adds a acpi_video_handles_brightness_key_presses() helper
function, making the code needing this functionality both easier to read
and more correct.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_video.c

diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index 3405f7a..2a649f3e 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -2072,6 +2072,18 @@
 	mutex_unlock(&register_count_mutex);
 }
 
+bool acpi_video_handles_brightness_key_presses(void)
+{
+	bool have_video_busses;
+
+	mutex_lock(&video_list_lock);
+	have_video_busses = !list_empty(&video_bus_head);
+	mutex_unlock(&video_list_lock);
+
+	return have_video_busses;
+}
+EXPORT_SYMBOL(acpi_video_handles_brightness_key_presses);
+
 /*
  * This is kind of nasty. Hardware using Intel chipsets may require
  * the video opregion code to be run first in order to initialise