Backlight always on

miniman
Attachment: config.zip (11.37 KB)
hi

i am on kernel 2.6.39.1 with marek patches.

why is my backlight always on?
what do i need to turn this off?

the tux and login promt disappear after a while,
but the display ist still on, that is the backlight roght???

already tried this ...

mini2440:~# cat /sys/devices/platform/s3c2410-lcd/graphics/fb0/blank
mini2440:~# echo "0" > /sys/devices/platform/s3c2410-lcd/graphics/fb0/blank
mini2440:~# cat /sys/devices/platform/s3c2410-lcd/graphics/fb0/blank
mini2440:~# echo "1" > /sys/devices/platform/s3c2410-lcd/graphics/fb0/blank
mini2440:~# cat /sys/devices/platform/s3c2410-lcd/graphics/fb0/blank
mini2440:~#

anyone know why, maybe missing something im kernel

thx
miniman

davef
The backlight just might be off.  In any case this might help:
http://www.friendlyarm.net/forum/topic/2575
found by searching <backlight>

miniman
i donīt have a /sys/devices/platform/s3c24xx_led.5

the tux and login promt (debian) disappear after a while,
but the display still shine, can see it very good at night.

is that the backlight?

davef
Well, I am operating with an updated 2.6.39.1 with all patches thanks to:
http://www.ptxdist.org/oselas/bsp/pengutronix/mini2440_bsp_en.html
and the display blanks after a few minutes of inactivity, which I assume to
be the backlight turning off.  The text disappears BUT you can still see
the scan lines.

There is another command for turning the backlight on and off in the thread
I linked to.  Does that not work?

fatbrain
Hi davef,
   Please refer to ptxdist mailing list there is a thread which has a fix
for the backlight issue, Search for "[Mini2440] Backlight GPIO". If i
recollect it was a kernel fix. 

Personally for me the fix worked. I was able to control backlight via soft
commands.

thanks

davef
fatbrain,

Thanks, but it's miniman with the problem :)  I am happy with my backlight.
 I recall the topic, but search on that forum seems to be down. I believe
any changes to the backlight would have been incorporated into the
OSELAS.BSP-Pengutronix-Mini2440-2011.06.0 release, but I'll check.

Cheers,
Dave

Juergen Beisert
If anybody has trouble with her/his backlight turning off after a while:
This happens only if the "Framebuffer Console support" is enabled. This
framework calls to switch off the backlight after some time of inactivity.
And this happens if the console shares the framebuffer with a graphical
application. That is why in the kernel in my board support package the
"Framebuffer Console support" is disabled. In this case the framebuffer is
owned only by the graphical application.