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 -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
