PROCESSOR-SDK-AM62X: PWM enablement in the kernel

HI ,

for enablement of backlight , we configured pwm in the dts as below :

&epwm0 {
pinctrl-names = "default";
pinctrl-0 = <&main_lvds_backlight_default>;
status = "okay";
};

and all other epwm &ecap nodes are disabled.

lcd_bl: backlight {
compatible = "pwm-backlight";
pinctrl-names = "default";
pinctrl-0 = <&main_lvds_backlight_default>;
brightness-levels = <0 10 20 30 40 50 60 70 80 90 99>;
default-brightness-level = <10>;pwms = <&epwm0 0 5000000 0>;
power-supply = <&vcc_3v3_sys>;
//enable-gpios = <&main_gpio1 7 GPIO_ACTIVE_HIGH>;
post-pwm-on-delay-ms = <10>;
pwm-off-delay-ms = <10>;
};

main_lvds_backlight_default: main-lvds-backlight-default{
pinctrl-single,pins = <

AM62X_IOPAD(0x0194, PIN_OUTPUT, 5) /* (B19) AM62X_ECAP1_IN_APWM_OUT\G */
>;
};

observations :

1. we are not able to enable backlight in the kernel .

2. we placed print stmts in the pwm_bl.c and we got below logs:

root@am62xx-evm:~# dmesg | grep pwm
[ 0.804956] line = 474 fun =pwm_backlight_probe
[ 0.804965] line = 244 fun =pwm_backlight_parse_dt
[ 1.275678] line = 474 fun =pwm_backlight_probe
[ 1.275690] line = 244 fun =pwm_backlight_parse_dt
[ 2.232911] line = 474 fun =pwm_backlight_probe
[ 2.232916] line = 244 fun =pwm_backlight_parse_dt
[ 2.243598] line = 407 fun =pwm_backlight_is_linear
[ 2.248665] line = 423 fun =pwm_backlight_initial_power_state
[ 2.253745] line = 113 fun =pwm_backlight_update_status
[ 2.259710] line = 70 fun =pwm_backlight_power_off
[ 6.703418] line = 113 fun =pwm_backlight_update_status
[ 6.703437] line = 70 fun =pwm_backlight_power_off

please share any info regd how to enable backlight in the kernel .

Thanks,

Naresh

Hi ,

Please help me anybody on this .

Thanks,

Naresh.

Hello Naresh,

Have you tried changing the backlight brightness setting? for example, reference post https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1128333/am6548-brightness-issue-of-pwm-backlight

Regards,

Nick