Tool/software: Linux
Hi All,
Problem-1:
When ever I am trying to turn off backlight LED using below command it's brightness level is high.
$ echo 0 > /sys/class/backlight/backlight/brightness
I checked with pulse (Oscilloscope) it is active high. I need to make it as active low (Full LED OFF).
My DTS Config is shown below:
lcd_bl: backlight {
compatible = "pwm-backlight";
pwms = <&ecap0 0 5000000 0>;
brightness-levels = <0 32 64 96 128 160 192 224 255>;
default-brightness-level = <7>;
};
panel {
compatible = "ti,tilcdc,panel";
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&lcd_pins_s0>;
backlight = <&lcd_bl>;
panel-info {
ac-bias = <255>;
ac-bias-intrpt = <0>;
dma-burst-sz = <16>;
bpp = <24>;
fdd = <0x80>;
sync-edge = <0>;
sync-ctrl = <1>;
raster-order = <0>;
fifo-th = <0>;
};
};
ecap0_pins: backlight_pins {
pinctrl-single,pins = <
0x164 ( PIN_OUTPUT | MUX_MODE0 )
/*AM33XX_IOPAD(0x964, MUX_MODE0)*/ /* eCAP0_in_PWM0_out.eCAP0_in_PWM0_out */
>;
};
&epwmss0 {
status = "okay";
ecap0: ecap@48300100 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&ecap0_pins>;
};
};
Used guide Link:
http://processors.wiki.ti.com/index.php/Sitara_Linux_LCDC_Porting_Guide
Problem-2:
I Tried to enable PWM manually by unbinding backlight driver using below commands.
Working steps: To Turn Off Backlight completly
echo out > /sys/class/gpio/gpio60/direction
echo backlight > /sys/bus/platform/drivers/pwm-backlight/unbind
echo 0 > /sys/class/pwm/pwmchip0/export
echo 1000000000 > /sys/class/pwm/pwmchip0/pwm0/period
echo 0 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle
echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable ----> (LED IS TURNED OFF COMPLETLY)
Working steps: To Turn On Backlight
echo 0 > /sys/class/pwm/pwmchip0/pwm0/enable
echo 0 > /sys/class/pwm/pwmchip0/unexport
echo backlight > /sys/bus/platform/drivers/pwm-backlight/bind
echo in > /sys/class/gpio/gpio60/direction ----> (LED IS TURNED ON )
NOW IF WE CONTROL THE BRIGHTNESS USING BELOW COMMAND IT IS NOT WORKING...
echo 3 > /sys/class/backlight/backlight/brightness
Please help me to solve this issue.
Thanks in advance!