On 08/03/2013 07:47 AM, Rafael J. Wysocki wrote: > On Friday, August 02, 2013 02:37:09 PM Felipe Contreras wrote: >> 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> > > Looks reasonable. > > Aaron, what do you think? Yes, the patch is correct, but I still prefer my own version :-) https://github.com/aaronlu/linux/commit/0a3d2c5b59caf80ae5bb1ca1fda0f7bf448b38c9 In case you want to take mine and mine needs refresh, please let me know and I can do the re-base, thanks. -Aaron > > Rafael > > >> --- >> >> 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) >> -- 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
