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iMX6quad  Brightness Control

Question asked by nandish sg on Jun 26, 2020
Latest reply on Jun 29, 2020 by nandish sg

Hi all.

 

I am trying to control the LVDS display brightness in imx6q in linux 4.9.87 kernel version. 

But when i give the commands in terminal for increment and decrement it work only high(ON) and low(OFF)  of the display. i am not able to see the any changes in brightness of display.

i am stuck at finding the the root cause and can any one help me how to resolve this issue,

the files list for related to the brightness control is as given below. and find the attached driver files zip.

 

1) /nxp-opensource/kernel_imx/drivers/pwm/core.c

2) /nxp-opensource/kernel_imx/drivers/pwm/pwm-imx.c

3) /nxp-opensource/kernel_imx/include/linux/pwm.h

4) /nxp-opensource/kernel_imx/drivers/video/backlight.c 

5) /nxp-opensource/kernel_imx/drivers/pwm/sysfs.c

6) /nxp-opensource/kernel_imx/drivers/regulator/pwm-regulator.c 

7) /nxp-opensource/kernel_imx/drivers/leds/leds-pwm.c

8) /nxp-opensource/kernel_imx/drivers/video/backlight/pwm_bl.c   // MAIN DRIVER FILE 

 

----------------------------------------------------------------------DISPLAY OFF (BLANK)-------------------------------

$ echo 0 > sys/class/backlight/backlight/brightness 
BL UPDATE STATUS : 0


PWM BACKLIGHT POWER OFF

 

CORE PWM CONFIG

---------------------------------------------------------------------------DISPLAY ON -----------------------------------------------

$ echo 1 > sys/class/backlight/backlight/brightness 

BL UPDATE STATUS : 1


INSIDE BL UPDATE STATUS FUN Brightness : 1


INSIDE DUTY CYCLE


lth Brightness :0

 

period : 0

 

Duty Cycle after compute : 0

 

pb->period is : 0


CORE PWM CONFIG

-------------------------------------------------------------------

$ cat sys/class/backlight/backlight/brightness
1

$ cat sys/class/backlight/backlight/max_brightness 
14

---------------------------------------------------------------------

 

 

Best Regrads 

SGN

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