[Gta04-owner] new lxde image: how does screen blanking work?

Dr. H. Nikolaus Schaller hns at goldelico.com
Sun May 12 12:02:39 CEST 2013

Am 11.05.2013 um 20:46 schrieb arne anka:

> addendum:
> what i see in kern.log is
> May 11 20:19:57 localhost kernel: [ 4933.941894] td028ttec1_panel_disable()
> May 11 20:19:57 localhost kernel: [ 4933.947113] gta04_disable_lcd()
> May 11 20:19:57 localhost kernel: [ 4933.950561] td028ttec1_panel_suspend()
> May 11 20:19:57 localhost kernel: [ 4934.025512] gta04_disable_lcd()

What you see above is the controlling of the LCD driver and electronics within the LCD module.

> and the screen turns ... white.

It does not automatically turn off backlight - this is why you see a white screen.

> which is quite the oppsoite to power saving.
> since when running console only the screen goes black and white only with X, i assume it has something to do with X.
> X is from unstable (not wheezy!), 1:7.7+3 and driver used is /usr/lib/xorg/modules/drivers/omapfb_drv.so (xserver-xorg-video-omap3, xorg.conf is the one from the lxde flashing image

Good question.

I have seen this behaviour in all kernels and installations.

Maybe the X server has some automatism to identify backlight control but I have never analysed that because it works for me with no obvoius problems.

-- hns

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