Screen blanks after ten minutes and won't come back

Question

Running a version of OpenEmbedded on a Raspberry Pi 2, the screen blanks after ten minutes.

1. This happens regardless of whether there is keyboard activity. It will blank while you're typing.

2. The keyboard still works, blindly typing shutdown -r now reboots it and brings the screen back.

3. X is not installed, so all the solutions using xset does not apply.

4. setterm is not installed, solutions using that doesn't work.

5. consoleblank=0 is already set on the kernel command line.

6. A serial terminal on /dev/ttyAMA0 continues to work.

7. Networking continues to work, you can still ssh to it.

8. Logs show absolutely nothing of use.

Any ideas on what else I can try? What is causing the screen to blank?

Answer 1

As usual, the moment you ask, you think of things to check.

It's an application that's blanking the screen. I stopped that application and the problem went away.

Specifically, in case someone else finds this via searth engine: it's for the Rpi port of Venus, the software for the CCGX. The gui-application, written in C++ using Qt-embedded, does something to blank the screen. After stopping that application, the screen now stays on (thanks to the consoleblank=0 boot parameter).

Since that application is a proprietary blob, I'll have to take it up with the manufacturer. It really shouldn't do this while running in "headless" mode :-)

Edit: Confirmed. When the screen blanks, /sys/class/graphics/fb0/blank contains a 1. Writing a zero to it brings the screen back.