Temporary garbage displayed after DISP_ON command (CFAG320240CX)


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Just got my CFAG320240CX-TFH-T display working over GPIO on the Soekris Net5501 using a NetBSD kernel and it works great. I do have a question, though:

Upon issuing the DisplayOn (0x59) command, I see text and graphical garbage being displayed on the screen. This is easily removed by clearing both the graphic and text layers with by sending NULL's and space characters respectively, but I'm curious if this garbage is coming from some sort of internal display storage, and if so, is it possible for me to replace it with something other than garbage (for instance, a pretty image).

Can somebody please provide some guidance here?..just looking for tools/code or an explanation how to do this, if possible.

Thank You,
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The garbage is most likely the uninitialized content of the onboard ram that is used to store the display data. You should clear those layers (or send data of your pretty picture) as part of your init routine, before you give the DisplayOn command.