[Bug 81515] [IVB Regression] Backlight is not adjustable and set at maximum level in kernels 3.16-rcX on HD 4000

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=81515

--- Comment #7 from Hohahiu <rakothedin at gmail.com> ---
Hello, Chris.

Finally I found a workaround ( had to go and see the code for an appropriate
kernel parameter). So with video.use_native_backlight=-1 (not sure what it
really means) the backlight works as before. The /sys/class/backlight folder
also contains:
acpi_video0  acpi_video1  intel_backlight.

As far as I understand in 3.16-rc1 the default value for use_native_backlight
was set to 1.

Just for reference:
linux at linux:/sys/class/backlight> grep '.*' /sys/class/dmi/id/*_* 2> /dev/null
/sys/class/dmi/id/bios_date:01/02/2013
/sys/class/dmi/id/bios_vendor:Insyde
/sys/class/dmi/id/bios_version:F.0B
/sys/class/dmi/id/board_asset_tag:Type2 - Board Asset Tag
/sys/class/dmi/id/board_name:1851
/sys/class/dmi/id/board_vendor:Hewlett-Packard
/sys/class/dmi/id/board_version:59.14
/sys/class/dmi/id/chassis_asset_tag:CNU229926N
/sys/class/dmi/id/chassis_type:10
/sys/class/dmi/id/chassis_vendor:Hewlett-Packard
/sys/class/dmi/id/chassis_version:Chassis Version
/sys/class/dmi/id/product_name:HP ENVY 15 Notebook PC
/sys/class/dmi/id/product_version:078F110000204810000620100
/sys/class/dmi/id/sys_vendor:Hewlett-Packard

So should I open new bug report against ACPI? Or what is the real problem?

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