Bootargs for enabling display omap

This articles talks about bootargs required to be added for enabling DSS. Starting with 2.6.34 (or L24.7) although DSS is enabled in defconfig, one needs to add some boot arguments to enable display and see penguin logos at the bootup time (skip to 27 min:14sec)

 

 

OMAP Display OVERLAYS Overlay here means a software overlay. In hardware it is called as pipeline.  -- Number of overlays for OMAP3: 3  overlay0: GFX,  overlay1: VID1,  overlay2: VID2  -- Number of overlays for OMAP4: 4  overlay0: GFX,  overlay1: VID1,  overlay2: VID2  overlay3: VID3  [edit] Set overlay properties Set overlay0 ON: echo "1" > /sys/devices/platform/omapdss/overlay0/enabled Set overlay0 OFF: echo "0" > /sys/devices/platform/omapdss/overlay0/enabled An overlay should be enabled if you want to see something on it. [edit] Reading overlay properties Read overlay1 input size cat /sys/devices/platform/omapdss/overlay0/input_size Reading overlay0's name cat /sys/devices/platform/omapdss/overlay0/name Reading output_size of overlay0 cat /sys/devices/platform/omapdss/overlay0/output_size Reading position of overlay0 cat /sys/devices/platform/omapdss/overlay0/position Reading screen_width of overlay0 cat /sys/devices/platform/omapdss/overlay0/screen_width Reading global_alpha of overlay0, Range: 0-255, 0=transparent 255=opaque cat /sys/devices/platform/omapdss/overlay0/global_alpha [edit] Set overlay's manager Set overlay0's manager as lcd echo "0" > /sys/devices/platform/omapdss/overlay0/enabled echo "lcd" > /sys/devices/platform/omapdss/overlay0/manager echo "1" > /sys/devices/platform/omapdss/overlay0/enabled

 

Zorder of an overlay [Specific to OMAP4 Not Applicable to OMAP3]

An object with a Z-order of 1 would be visually "underneath" an object with a Z-order of 2 or greater.

The default zorders are:

Overlay 0 -> 0 
Overlay 1 -> 1 
Overlay 2 -> 2 
Overlay 3 -> 3 

To change the zorder the following command can be used:

# Make GFX topmost:  echo "3" > /sys/devices/platform/omapdss/overlay0/zorder