===================================================================
@@ -805,12 +805,19 @@ acpi_video_init_brightness(struct acpi_v
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;
@@ -818,25 +825,19 @@ acpi_video_init_brightness(struct acpi_v
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.
- */
-
- 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;
- }
+ br->flags._BQC_use_index = (level == max_level ? 0 : 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));
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> --- drivers/acpi/video.c | 43 ++++++++++++++++++++++--------------------- 1 file changed, 22 insertions(+), 21 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html