Commit 8ab58e8e authored by Linus Torvalds's avatar Linus Torvalds Committed by Rafael J. Wysocki
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ACPI / video: Fix backlight taking 2 steps on a brightness up/down keypress 

In various scenarious userspace will respond to brightness up/down keypresses
by increasing/decreasing the backlight brightness itself. If the kernel then
also changes the brightness this results in the brightness having changed 2
steps for a single keypress which is undesirable. See e.g. :

https://bugs.launchpad.net/gnome-settings-daemon/+bug/527157
http://askubuntu.com/questions/173921/why-does-my-thinkpad-brightness-control-skip-steps

This commit delays responding to brightness up/down keypresses by 100 ms and
if userspace in that time responds by changing the backlight itself, cancels
the kernels own handling of these keypresses, fixing the 2 steps issue.

Link: http://marc.info/?l=linux-kernel&m=140535721100839&w=2


[hdegoede@redhat.com: Move the delayed_work struct into struct
 acpi_video_device instead of having it as a global]
[hdegoede@redhat.com: Keep brightness_switch_enabled as a boolean and always
 delay the keypress handling]
Tested-by: default avatarHans de Goede <hdegoede@redhat.com>
Tested-by: default avatarBjørn Mork <bjorn@mork.no>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 9a3c4145

drivers/acpi/video.c

+27 −17
Original line number Diff line number Diff line
@@ -204,6 +204,8 @@ struct acpi_video_device { 
	struct acpi_video_device_flags flags;

	struct acpi_video_device_cap cap;

	struct list_head entry;

	struct delayed_work switch_brightness_work;

	int switch_brightness_event;

	struct acpi_video_bus *video;

	struct acpi_device *dev;

	struct acpi_video_device_brightness *brightness;
@@ -230,8 +232,7 @@ static int acpi_video_device_lcd_get_level_current( 
			unsigned long long *level, bool raw);

static int acpi_video_get_next_level(struct acpi_video_device *device,

				     u32 level_current, u32 event);

static int acpi_video_switch_brightness(struct acpi_video_device *device,

					 int event);

static void acpi_video_switch_brightness(struct work_struct *work);



static bool acpi_video_use_native_backlight(void)

{
@@ -275,6 +276,7 @@ static int acpi_video_set_brightness(struct backlight_device *bd) 
	int request_level = bd->props.brightness + 2;

	struct acpi_video_device *vd = bl_get_data(bd);



	cancel_delayed_work(&vd->switch_brightness_work);

	return acpi_video_device_lcd_set_level(vd,

				vd->brightness->levels[request_level]);

}
@@ -1188,6 +1190,8 @@ acpi_video_bus_get_one_device(struct acpi_device *device, 
	data->device_id = device_id;

	data->video = video;

	data->dev = device;

	INIT_DELAYED_WORK(&data->switch_brightness_work,

			  acpi_video_switch_brightness);



	attribute = acpi_video_get_device_attr(video, device_id);
@@ -1410,15 +1414,18 @@ acpi_video_get_next_level(struct acpi_video_device *device, 
	}

}



static int

acpi_video_switch_brightness(struct acpi_video_device *device, int event)

static void

acpi_video_switch_brightness(struct work_struct *work)

{

	struct acpi_video_device *device = container_of(to_delayed_work(work),

			     struct acpi_video_device, switch_brightness_work);

	unsigned long long level_current, level_next;

	int event = device->switch_brightness_event;

	int result = -EINVAL;



	/* no warning message if acpi_backlight=vendor or a quirk is used */

	if (!acpi_video_verify_backlight_support())

		return 0;

		return;



	if (!device->brightness)

		goto out;
@@ -1440,8 +1447,6 @@ acpi_video_switch_brightness(struct acpi_video_device *device, int event) 
out:

	if (result)

		printk(KERN_ERR PREFIX "Failed to switch the brightness\n");



	return result;

}



int acpi_video_get_edid(struct acpi_device *device, int type, int device_id,
@@ -1609,6 +1614,16 @@ static void acpi_video_bus_notify(struct acpi_device *device, u32 event) 
	return;

}



static void brightness_switch_event(struct acpi_video_device *video_device,

				    u32 event)

{

	if (!brightness_switch_enabled)

		return;



	video_device->switch_brightness_event = event;

	schedule_delayed_work(&video_device->switch_brightness_work, HZ / 10);

}



static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)

{

	struct acpi_video_device *video_device = data;
@@ -1626,28 +1641,23 @@ static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data) 


	switch (event) {

	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:	/* Cycle brightness */

		if (brightness_switch_enabled)

			acpi_video_switch_brightness(video_device, event);

		brightness_switch_event(video_device, event);

		keycode = KEY_BRIGHTNESS_CYCLE;

		break;

	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:	/* Increase brightness */

		if (brightness_switch_enabled)

			acpi_video_switch_brightness(video_device, event);

		brightness_switch_event(video_device, event);

		keycode = KEY_BRIGHTNESSUP;

		break;

	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:	/* Decrease brightness */

		if (brightness_switch_enabled)

			acpi_video_switch_brightness(video_device, event);

		brightness_switch_event(video_device, event);

		keycode = KEY_BRIGHTNESSDOWN;

		break;

	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:	/* zero brightness */

		if (brightness_switch_enabled)

			acpi_video_switch_brightness(video_device, event);

		brightness_switch_event(video_device, event);

		keycode = KEY_BRIGHTNESS_ZERO;

		break;

	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:	/* display device off */

		if (brightness_switch_enabled)

			acpi_video_switch_brightness(video_device, event);

		brightness_switch_event(video_device, event);

		keycode = KEY_DISPLAY_OFF;

		break;

	default:

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