default or selected kernelversion does not have config value CONFIG_BACKLIGHT_LCD_SUPPORT.
Result is shown for kernelversion 6.9.9

Backlight & LCD device support

configname: CONFIG_BACKLIGHT_LCD_SUPPORT

Linux Kernel Configuration
└─>Device Drivers
└─>Graphics support
└─>Backlight & LCD device support
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Enable this to be able to choose the drivers for controlling the
backlight and the LCD panel on some platforms, for example on PDAs.


is selected by
CONFIG_FB_OLPC_DCON

is depended by
CONFIG_FB_BACKLIGHT