On 08/04/2013 06:07 AM, Rafael J. Wysocki wrote: > On Saturday, August 03, 2013 08:10:12 PM Aaron Lu wrote: >> On 08/03/2013 07:23 PM, Rafael J. Wysocki wrote: >>> On Saturday, August 03, 2013 05:46:02 PM Aaron Lu wrote: >>>> On 08/03/2013 08:26 AM, Rafael J. Wysocki wrote: >>>>> On Friday, August 02, 2013 10:52:09 PM Aaron Lu wrote: >>>>>> On 08/02/2013 10:41 PM, Rafael J. Wysocki wrote: >>>>>>> On Friday, August 02, 2013 01:55:47 PM Aaron Lu wrote: >>>>>>>> On 03/08/2013 03:39 AM, Seth Forshee wrote: >>>>>>>>> Windows 8 requires all backlight interfaces to report 101 brightness >>>>>>>>> values, and as a result we're starting to see machines with that many >>>>>>>>> brightness levels in _BCL. For machines which send these notifications >>>>>>>>> when the brightness up/down keys are pressed this means a lot of key >>>>>>>>> presses to get any kind of noticeable change in brightness. >>>>>>>>> >>>>>>>>> For a while now we've had the ability to disable in-kernel handling of >>>>>>>>> notifications via the video.brightness_switch_enabled parameter. Change >>>>>>>>> this to default to off, and let userspace choose more reasonable >>>>>>>>> increments for changing the brightness. >>>>>>>> >>>>>>>> I just found one more reason for this param to default 0. >>>>>>> >>>>>>> Do you mean video.brightness_switch_enabled? >>>>>> >>>>>> Yes. >>>>>> >>>>>>> >>>>>>>> We are going to separate the backlight interface control and event >>>>>>>> notification functionalities of the ACPI video module, it is highly >>>>>>>> possible a lot of systems will use a combination of the event >>>>>>>> notification handler and intel_backlight interface. So it doesn't make >>>>>>>> sense to let video module to do any adjustment on its own if user space >>>>>>>> has chosen a different interface to use. Actually, it can cause problems >>>>>>>> as in ASUS's case: >>>>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=52951 >>>>>>>> >>>>>>>> The problem there is, on hotkey brightness up, the video module will >>>>>>>> adjust the brightness level first and since its _BQC is broken, it gets >>>>>>>> a wrong number(too low or too high or whatever) and then does the _BCM >>>>>>>> call. The _BCM method works. Then user space picks the intel_backlight >>>>>>>> to do the adjustment, but since the _BCM already sets a wrong value, the >>>>>>>> user space's adjustment is affected too. The result is, user has only >>>>>>>> two visible levels, very low and very high. >>>>>>>> >>>>>>>> This only occurs on -rc3, since we removed the >>>>>>>> acpi_video_verify_backlight_support from acpi_video_switch_brightness >>>>>>>> function. >>>>>>> >>>>>>> What did we do before -rc2? Did we address that in any way? >>>>>> >>>>>> No, before rc2, backlight is broken on that system. >>>>> >>>>> Well, it will have to stay that way in 3.11 I'm afraid, unless we have a fix >>>>> or a workaround that is *guaranteed* not to introduce any new issues on any >>>>> systems. >>>>> >>>>>> In rc2, we added the win8 patch and a fix patch for the hotkey, then >>>>>> the ACPI video module's backlight control and in kernel brightness >>>>>> handling is disabled. With the working hotkey and intel_backlight, rc2 >>>>>> works for the system. Then with the revert in rc3, user needs to choose >>>>>> intel_backlight in xorg.conf but the in kernel brightness handling from >>>>>> ACPI video module is back. Since video module is broken, it breaks the >>>>>> backlight hotkey functionality. >>>>> >>>>> I guess we need to revert the hotkey fix too (that is efaa14c, right?) >>>>> then, is that correct? And try to do something smarter for 3.12? >>>> >>>> With or without commit efaa14c, hotkey for backlight is broken out of >>>> box for the affected systems(ASUS N56VZ and N56VJ). But with that commit, >>>> user has a chance of getting a working backlight with hotkey by specifying >>>> intel_backlight and adding the video.brightness_switch_enabled=0. So I >>>> think we can keep that commit. >>> >>> What about the "boot to black screen" problem, then? >> >> You mean this one? >> https://lkml.org/lkml/2013/7/30/814 > > Yes. :-) That is due to the broken _BQC provided by firmware, not that commit. After we enhance the quirk for _BQC, the problem will be gone. -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
