Keeping backlight off on startup

Technical Support
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1

Hi,

I need to keep the display (or backlight) off while the startup process. Is it possible to control that behaviour?

Renato

2

Which carrier board you are display you are using?

3

Both Iris V1.1A and V2.0A

4

Hi @Renato ,

Why do you need to keep the display off?

It is possible to change the backlight using the backlight PWM, normally the path to the PWM is /sys/class/backlight/backlight/brightness, is it enough for you?

Best regards,

Daniel Morais

5

I need to keep the display off because the power supply is very limited in current. The system cannot start because that. My idea is either keep the display off or reduce the brightness at the beggining. But I need to configure this before the splash screen appear.

6

Hi @Renato,

There are two physical interfaces that turn on the display. There is a GPIO that enables the backlight and there is also a PWM that changes the brightness.

One possibility is to disable the GPIO on U-Boot and enable it again when Linux is up. You can check the correct GPIO used by the backlight on the datasheet, normally it has the name BL_ON.

Best regards,

Daniel Morais