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? Rafael -- 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
