LVDS Backlight Control questions

  • In fsimx6-V3 / (Armstone A9) the backlight brightness is set as shown below:

    cat /sys/devices/soc0/backlight_ldb//backlight/backlight_ldb/max_brightness /* gives -> 15 */
    echo 15 > /sys/devices/soc0/backlight_ldb//backlight/backlight_ldb/brightness /* sets it to maximum */


    • What are possible values/strings for /sys/devices/soc0/backlight_ldb/backlight/backlight_ldb/power/control ? The default is "auto"!
    • How do I access Pin-24 of the LCD FI-S25S connector in order to manually switch off/on the backlight ?
  • power/control is a setting that is available for all devices. It is the so-called runtime-auto flag. This flag determines, whether the device may be automatically put to a sleep or suspend mode when not needed (setting "auto") or if it should stay active all the time (setting "on"). This is just a power saving feature at runtime, it is not honored when the system as a whole is put to a suspend state like suspend-to-ram, etc. Then the device is shut down whether this flag is set to "on" or not. So the possible values are "on" and "auto".

    To access pin 24, simply write zero or non-zero to the brightness. The brightness value not only drives the BACKLIGHT_PWM value, it switches the BACKLIGHT_ON signal, too.

    Your F&S Support Team

    F&S Elektronik Systeme GmbH
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