On 08/03/2013 07:34 PM, Rafael J. Wysocki wrote: > On Saturday, August 03, 2013 04:14:04 PM Aaron Lu wrote: >> 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. > > Well, I prefer simpler, unless there's a good reason to use more complicated. > > Why exactly do you think your version is better? As explained here: https://lkml.org/lkml/2013/8/2/81 https://lkml.org/lkml/2013/8/2/112 And for the demo broken _BQC, mine patch will disable _BQC while still make the backlight work, and this patch here is testing the max brightness level and may fail. -Aaron -- 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
