If the _BCL package is descending, the first level (br->levels[2]) will be 0, and if the number of levels matches the number of steps, we might confuse a returned level to mean the index. For example: current_level = max_level = 100 test_level = 0 returned level = 100 In this case 100 means the level, not the index, and _BCM failed. But if the _BCL package is descending, the index of level 0 is also 100, so we assume _BQC is indexed, when it's not. This causes all _BQC calls to return bogus values causing weird behavior from the user's perspective. For example: xbacklight -set 10; xbacklight -set 20; would flash to 90% and then slowly down to the desired level (20). The solution is simple; test anything other than the first level (e.g. 1). Signed-off-by: Felipe Contreras <felipe.contreras@xxxxxxxxx> --- On top of this we might want to test yet another value, because br->levels[3] might be the current value (although very unlikely). drivers/acpi/video.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c index 0ec434d..e1284b8 100644 --- a/drivers/acpi/video.c +++ b/drivers/acpi/video.c @@ -689,7 +689,7 @@ static int acpi_video_bqc_quirk(struct acpi_video_device *device, * Some systems always report current brightness level as maximum * through _BQC, we need to test another value for them. */ - test_level = current_level == max_level ? br->levels[2] : max_level; + test_level = current_level == max_level ? br->levels[3] : max_level; result = acpi_video_device_lcd_set_level(device, test_level); if (result) -- 1.8.4.rc1 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
