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? 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
