Commit e047cca6 authored by Zhang Rui's avatar Zhang Rui Committed by Len Brown
Browse files

ACPI video: handle indexed _BQC correctly 

In the current code, for a box with an indexed _BQC method, we
1. get the current brightness level by evaluating _BQC
2. set the value gotten in step 1 to _BCM
3. get the current brightness level again
4. set the _BQC_use_index flag if the results gotten
   in step 1 and in step 3 don't equal.

But this logic doesn't work actually, because the _BQC_use_index
is not set when acpi_video_device_lcd_set_level is invoked.
This results in a failure in step 2.
http://bugzilla.kernel.org/show_bug.cgi?id=12249#c83



Now, we set the _BQC_use_index flag after invoking _BQC for the first
time. And reevaluate the _BQC to get the correct brightness level.

Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent d8482238

drivers/acpi/video.c

+22 −21
Original line number Diff line number Diff line
@@ -807,12 +807,19 @@ acpi_video_init_brightness(struct acpi_video_device *device) 
	br->flags._BCM_use_index = br->flags._BCL_use_index;



	/* _BQC uses INDEX while _BCL uses VALUE in some laptops */

	br->curr = max_level;

	br->curr = level_old = max_level;



	if (!device->cap._BQC)

		goto set_level;



	result = acpi_video_device_lcd_get_level_current(device, &level_old);

	if (result)

		goto out_free_levels;



	result = acpi_video_device_lcd_set_level(device, br->curr);

	/*

	 * Set the level to maximum and check if _BQC uses indexed value

	 */

	result = acpi_video_device_lcd_set_level(device, max_level);

	if (result)

		goto out_free_levels;
@@ -820,25 +827,19 @@ acpi_video_init_brightness(struct acpi_video_device *device) 
	if (result)

		goto out_free_levels;



	if ((level != level_old) && !br->flags._BCM_use_index) {

		/* Note:

		 * This piece of code does not work correctly if the current

		 * brightness levels is 0.

		 * But I guess boxes that boot with such a dark screen are rare

		 * and no more code is needed to cover this specifial case.

		 */

	br->flags._BQC_use_index = (level == max_level ? 0 : 1);



		if (level_ac_battery != 2) {

			/*

			 * For now, we don't support the _BCL like this:

			 * 16, 15, 0, 1, 2, 3, ..., 14, 15, 16

			 * because we may mess up the index returned by _BQC.

			 * Plus: we have not got a box like this.

			 */

			ACPI_ERROR((AE_INFO, "_BCL not supported\n"));

		}

		br->flags._BQC_use_index = 1;

	}

	if (!br->flags._BQC_use_index)

		goto set_level;



	if (br->flags._BCL_reversed)

		level_old = (br->count - 1) - level_old;

	level_old = br->levels[level_old];



set_level:

	result = acpi_video_device_lcd_set_level(device, level_old);

	if (result)

		goto out_free_levels;



	ACPI_DEBUG_PRINT((ACPI_DB_INFO,

			  "found %d brightness levels\n", count - 2));

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