ACPI: video: create "brightness_switch_enabled" modparam
Introduce new module parameter for brightness control.
"brightness_switch_enabled" is set by default which means
nothing changes upon brightness switch events.
When "brightness_switch_enabled" is cleared via
"echo 0 > /sys/module/video/parameters/brightness_switch_enabled",
ACPI will not try to change the brightness level any more.
Either X will take charge of this or users can change the brightness level
by poking /sys/class/backlight/acpi_videoX/...
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index bd77e81..b1a56bf 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -72,6 +72,9 @@
MODULE_DESCRIPTION("ACPI Video Driver");
MODULE_LICENSE("GPL");
+static int brightness_switch_enabled = 1;
+module_param(brightness_switch_enabled, bool, 0644);
+
static int acpi_video_bus_add(struct acpi_device *device);
static int acpi_video_bus_remove(struct acpi_device *device, int type);
@@ -1850,27 +1853,32 @@
switch (event) {
case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS: /* Cycle brightness */
- acpi_video_switch_brightness(video_device, event);
+ if (brightness_switch_enabled)
+ acpi_video_switch_brightness(video_device, event);
acpi_bus_generate_proc_event(device, event, 0);
keycode = KEY_BRIGHTNESS_CYCLE;
break;
case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS: /* Increase brightness */
- acpi_video_switch_brightness(video_device, event);
+ if (brightness_switch_enabled)
+ acpi_video_switch_brightness(video_device, event);
acpi_bus_generate_proc_event(device, event, 0);
keycode = KEY_BRIGHTNESSUP;
break;
case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS: /* Decrease brightness */
- acpi_video_switch_brightness(video_device, event);
+ if (brightness_switch_enabled)
+ acpi_video_switch_brightness(video_device, event);
acpi_bus_generate_proc_event(device, event, 0);
keycode = KEY_BRIGHTNESSDOWN;
break;
case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS: /* zero brightnesss */
- acpi_video_switch_brightness(video_device, event);
+ if (brightness_switch_enabled)
+ acpi_video_switch_brightness(video_device, event);
acpi_bus_generate_proc_event(device, event, 0);
keycode = KEY_BRIGHTNESS_ZERO;
break;
case ACPI_VIDEO_NOTIFY_DISPLAY_OFF: /* display device off */
- acpi_video_switch_brightness(video_device, event);
+ if (brightness_switch_enabled)
+ acpi_video_switch_brightness(video_device, event);
acpi_bus_generate_proc_event(device, event, 0);
keycode = KEY_DISPLAY_OFF;
break;