iMX6quad Brightness Control

[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

[nandish_sg]

Hi igor,

Thanks for your quick reply. i tried for the same but it not works for me again same result no brightness control, 

Can any one help me to resolve this issue, if you need any input from me please let me know.

BR

SGN 

[igorpadykov]

Hi nandish

one can try to test with nxp L4.9.88 kernel (check for "pwm") :

imx6qdl-sabresd.dtsi\dts\boot\arm\arch - linux-imx - i.MX Linux kernel 

Best regards
igor
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