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? > 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? > So either we make this param default to 0, or we make a new > function to avoid brightness switch in video module for Win8 systems. > > I prefer to set this param to 0 by default. What do you guys think? That depends on what we did earlier. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
