Hardkernel LCD screen doesn't have backlight controls (X2/wheezy/3.8 kernel)

[declanmalone]

CONFIG_BACKLIGHT_PWM is not set in the current/latest kernel. Turning it on doesn't help

zcat /proc/config.gz |grep BACKLIGHT
CONFIG_SAMSUNG_DEV_BACKLIGHT=y
# CONFIG_FB_BACKLIGHT is not set
CONFIG_BACKLIGHT_LCD_SUPPORT=y
CONFIG_BACKLIGHT_CLASS_DEVICE=y
# CONFIG_BACKLIGHT_GENERIC is not set
CONFIG_BACKLIGHT_PWM=m   <--- turned on
# CONFIG_BACKLIGHT_ADP8860 is not set
# CONFIG_BACKLIGHT_ADP8870 is not set
# CONFIG_BACKLIGHT_LM3630 is not set
# CONFIG_BACKLIGHT_LM3639 is not set
# CONFIG_BACKLIGHT_LP855X is not set
CONFIG_HID_PICOLCD_BACKLIGHT=y
CONFIG_LEDS_TRIGGER_BACKLIGHT=y

Boot messages:

$ dmesg | grep back
[    3.977660] pwm-backlight pwm-backlight.0: unable to request PWM, trying legacy API
[    3.982264] pwm-backlight pwm-backlight.0: unable to request legacy PWM
[    4.110729] platform pwm-backlight.0: Driver pwm-backlight requests probe deferral
[    4.289334] pwm-backlight pwm-backlight.0: unable to request PWM, trying legacy API
[    4.302308] pwm-backlight pwm-backlight.0: unable to request legacy PWM
[    4.311763] platform pwm-backlight.0: Driver pwm-backlight requests probe deferral
[    4.386515] pwm-backlight pwm-backlight.0: unable to request PWM, trying legacy API
[    4.394205] pwm-backlight pwm-backlight.0: unable to request legacy PWM
[    4.400775] platform pwm-backlight.0: Driver pwm-backlight requests probe deferral

Older XU kernel (latest, 3.4.91) has /sys/class/ entry for pwm-backlight.0 with working control files. This kernel has the directory, but no controls.