iMX6quad Brightness Control

nandish_sg — Fri, 26 Jun 2020 14:17:15 GMT

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

Re: iMX6quad Brightness Control

igorpadykov — Fri, 26 Jun 2020 23:46:14 GMT

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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Re: iMX6quad Brightness Control

nandish_sg — Mon, 29 Jun 2020 11:28:27 GMT

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.

SGN

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iMX6quad Brightness Control

Re: iMX6quad Brightness Control

Re: iMX6quad Brightness Control