dmesg:

acpi device:03: registered as cooling_device2
input: Video Bus as /class/input/input7
ACPI: Video Device [VID] (multi-head: yes  rom: no  post: no)

xrandr --prop:

Screen 0: minimum 320 x 200, current 1024 x 768, maximum 1024 x 1024
VGA disconnected (normal left inverted right x axis y axis)
LVDS connected 1024x768+0+0 (normal left inverted right x axis y axis) 246mm x 185mm
	EDID_DATA:
		00ffffffffffff0030ae004000000000
		000f010380191278eaed7591574f8b26
		21505421080001010101010101010101
		01010101010128150040410026301888
		3600f6b900000018ed10004041002630
		18883600f6b9000000180000000f0061
		43326143280f01004ca3584a000000fe
		004c544e313231584a2d4c30370a0000
	PANEL_FITTING: full
		supported: center       full_aspect  full        
	BACKLIGHT_CONTROL: kernel
		supported: native       legacy       combination  kernel      
	BACKLIGHT: 5 (0x00000005) range:  (0,15)
   1024x768       50.0*+   60.0     40.0  
   800x600        60.3  
   640x480        60.0     59.9

Xorg log:

(II) intel(0): found backlight control method /sys/class/backlight/acpi_video0

sysfs:

/sys/class/backlight/acpi_video0/actual_brightness:5
/sys/class/backlight/acpi_video0/bl_power:0
/sys/class/backlight/acpi_video0/brightness:5
/sys/class/backlight/acpi_video0/max_brightness:15
/sys/class/backlight/acpi_video0/power/wakeup:
/sys/class/backlight/acpi_video0/subsystem/acpi_video0/bl_power:0
/sys/class/backlight/acpi_video0/subsystem/acpi_video0/brightness:5
/sys/class/backlight/acpi_video0/subsystem/acpi_video0/actual_brightness:5
/sys/class/backlight/acpi_video0/subsystem/acpi_video0/max_brightness:15
/sys/class/backlight/acpi_video0/subsystem/acpi_video0/power/wakeup: