Comment 99 for bug 333386

brightness works out of the box (without boot parameter) with your proposed kernel... here DMESG detail:
[ 8.769760] acer-wmi: Acer Laptop ACPI-WMI Extras
[ 8.770046] ACPI: Using less restrictive video detection
[ 8.770047] acer-wmi: Brightness must be controlled by generic video driver
[ 8.770119] acer-wmi: software RFKILL enabled

Anyway FN-keys issue is still present, the same as before:

[Initial status of the machine is BRIGHTNESS_MAX]
If I press FN+BRIGHTNESS_DOWN just once
       > It increases (correctly) to BRIGHTNESS_MAX-1 but then *immediately*
           goes to BRIGHTNESS_MIN (wrong)

[Initial status of the machine is BRIGHTNESS_MIN]
If I press FN + BRIGHTNESS_UP just once
       > It increases to BRIGHTNESS_MAX+1 (correctly) but then immediately
           increases again, so finally it goes to BRIGHTNESS_MAX+2 (wrong)
If I press FN + BRIGHTNESS_UP again
       > It returns to BRIGHTNESS_MAX+1 (wrong)

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