kernel compilation error

Kernel 3.2 compilation for mini2440 the error comes in the file
linux-3.2/drivers/video/backlight/pwm_bl.c

in function pwm_backlight_suspend
            undefined reference to pwm_set_duty_ns, pwm_stop

in function pwm_backlight_remove
          undefined reference to pwm_set_duty_ns,pwm_stop,pwm_release      

in function pwm_backlight_update_status
          undefined reference to pwm_set_duty_ns,pwm_stop,pwm_start 
.
.
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Pls help some one how to overcome

Tarn

Common problem is that the compiler can't find those functions.  There
should be a file called pwm_blc.h which defines those functions.  

Can you find that file in the same directory as pwm_blc.c