[Bug 84561] New: Intel backlight does not adjust, but only turns on/off in kernel 3.16 on Samsung 880Z5E laptop

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=84561

            Bug ID: 84561
           Summary: Intel backlight does not adjust, but only turns on/off
                    in kernel 3.16 on Samsung 880Z5E laptop
           Product: Drivers
           Version: 2.5
    Kernel Version: 3.16.2
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Video(DRI - Intel)
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: vitalif at yourcmc.ru
                CC: intel-gfx-bugs at lists.freedesktop.org
        Regression: No

Hi!

After upgrading from kernel 3.14 to 3.16 on a Samsung 880Z5E laptop (with dual
Intel HD 4000 and Radeon 8770M cards), the intermediate % of backlight don't
work.

I.e. /sys/class/backlight/intel_backlight is there with max_brightness=4882 and
type=raw, but all brightness levels > 0 result in full brightness, and
brightness level = 0 results in the screen turned off. The same is on the
brightness adjustment UI: 0% is "turned off", everything greater than 0% is
full brightness.

(although when the screen is turned on after being turned off, the backlight
turns on smoothly)

acpi_backlight=vendor and video.use_native_backlight=1 also don't work.

What other details do you need? acpidump, dmidecode?

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