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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: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Zhang Rui 2009-04-09 14:24:35 +08:00 committed by Len Brown
parent d848223808
commit e047cca66c
1 changed files with 21 additions and 20 deletions
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41
drivers/acpi/video.c
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@ -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));