BSP is linux L3.14.28_1.0.0-ga，How to adjust the brightness of the screen

[haibohe]

BSP is linux L3.14.28_1.0.0-ga

Boot setting：bootargs_mmc=setenv bootargs ${bootargs} root=/dev/mmcblk3p1 rootwait rw video=mxcfb0:dev=ldb,if=RGB666 ldb=sin0

Through the LVDS0 output, the screen is very dark

How to adjust the brightness of the screen

Please help

thanks

[igorpadykov · Accepted solution]

Hi haibo

The IPU backlight driver implements IPU PWM backlight control for panels. It exports a

sys control file under /sys/class/backlight/pwm-backlight.0/brightness to user space.

Please refer to attached Linux Manual sect.6.2.2 IPU Backlight Driver. Also link below

may be useful.

iMX6Q display adjustment

Best regards

igor

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[haibohe]

Can not be modified

root@imx6qsabresd:/sys/class/backlight/backlight.28# ls

actual_brightness  brightness  max_brightness  subsystem  uevent

bl_power           device      power           type

root@imx6qsabresd:/sys/class/backlight/backlight.28# cat actual_brightness

7

root@imx6qsabresd:/sys/class/backlight/backlight.28# cat max_brightness   

Harry: File=drivers/video/backlight/backlight.c: Func=max_brightness_show: Line=211 max_brightness=7

7

root@imx6qsabresd:/sys/class/backlight/backlight.28# cat brightness    

Harry: File=drivers/video/backlight/backlight.c: Func=brightness_show: Line=162 max_brightness=7

7

root@imx6qsabresd:/sys/class/backlight/backlight.28# echo 128 > max_brightness

-sh: echo: write error: Input/output error

root@imx6qsabresd:/sys/class/backlight/backlight.28# echo 128 > brightness

Harry: File=drivers/video/backlight/backlight.c: Func=brightness_store: Line=178 max_brightness=1

-sh: echo: write error: Invalid argument

root@imx6qsabresd:/sys/class/backlight/backlight.28# cat > brightness

120

Harry: File=drivers/video/backlight/backlight.c: Func=brightness_store: Line=178 max_brightness=1

cat: write error: Invalid argument

root@imx6qsabresd:/sys/class/backlight/backlight.28#