Philipp, Fabio, I was able to verify that the PREs do indeed overrun their allocated ocram area.
Section 38.5.1 of the iMX6QuadPlus manual indicates the ocram size required: width(pixels) x 8 lines x 4 bytes. For 2048 pixels max, this comes to 64K. This is what the PRE driver allocates. So far, so good. The trouble starts when we're displaying a section of a much wider bitmap. This happens in X when using two displays. e.g.: HDMI 1920x1088 LVDS 1280x800 X bitmap 3200x1088, left side displayed on HDMI, right side on LVDS. In such a case, the stride will be much larger than the width of a display scanline. This is where things start to go very wrong. I found that the ocram area used by the PREs increases with the stride. I experimentally found a formula: ocam_used = display_widthx8x4 + (bitmap_width-display_width)x7x4 As the stride increases, the PRE eventually overruns the ocram and... ends up in the "ocram aliased" area, where it overwrites the ocram in use by the vpu/coda ! I could not find any PRE register setting that changes the used ocram area. Sven
