LCD brightness control on da850/omap-l138
From Texas Instruments Wiki
On da850/omap-l138 based boards LCD backlight is connected to:
- GPIO2/eCAP on variant 0 Logic PD EVMs.
- GPIO2/eHRPWM on SpectrumDigital variant 1 EVM and on Rev3 Logic PD EVMs.
Enabling PWM backlight
Follow below steps to enable PWM backlight on 03.22 based releases:
- Disable SPI as SPI flash chipselect line shared with backlight.
- Enable eHRPWM as specified here
- Then enable PWM backlight driver as below:
Device Drivers ---> Graphics support ---> [*]Backlight & LCD device support ---> <*> Lowlevel Backlight controls; <*> Generic PWM based Backlight Driver
Steps to verify brightness control
# echo <brightness_value> > /sys/class/backlight/pwm-backlight/brightness
brightness_value can be varied from 0-250. 0 corresponds to 0% dutycycle and 250 corresponds to 100%.