SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The overlay manager is configured using the Z-order parameter. The Z-order value defined for each pipeline indicates the visibility order to the window on the screen. If the Z-order value of window A is lower than the Z-order to layer B, layer A is displayed below layer B. The transparency color keys and the alpha blending factors are then used to blend the layers together (see Section 11.2.4.13.1.2, DISPC ALPHA Blender, and Section 11.2.4.13.1.3, DISPC Transparency Color Keys). The Z-order is enabled by setting the DISPC_GFX_ATTRIBUTES[25] ZORDERENABLE bit or the DISPC_VIDp_ATTRIBUTES[25] ZORDERENABLE bit to 0x1 and by defining the Z-order in the DISPC_GFX_ATTRIBUTES[27:26] and DISPC_VIDp_ATTRIBUTES[27:26] ZORDER bit fields. Table 11-83 summarizes the register settings to enable and set the Z-order of a pipeline. Table 11-83 shows the default Z-order values when LCDALPHABLENDERENABLE and ZORDERENABLE are disabled.
Pipeline | LCDALPHA BLENDERENABLE(1) | ZORDERENABLE | ZORDER | Resulting Z-Order Number |
---|---|---|---|---|
GFX | 0 | 0 | Don't care | 0 |
0 | 1 | ZORDER | ZORDER | |
1 | Don't care | Don't care | 3 | |
VID1 | 0 | 0 | Don't care | 1 |
0 | 1 | ZORDER | ZORDER | |
1 | Don't care | Don't care | 0 | |
VID2 | 0 | 0 | Don't care | 2 |
0 | 1 | ZORDER | ZORDER | |
1 | Don't care | Don't care | 1 | |
VID3 | 0 | 0 | Don't care | 3 |
0 | 1 | ZORDER | ZORDER | |
1 | Don't care | Don't care | 2 |
Figure 11-74 shows the architecture of the priority rule.
The height and width of each enabled layer (pipeline) must be defined in the SIZEY and SIZEX bit fields DISPC_GFX_SIZE[27:16][10:0]/ DISPC_VIDp_SIZE[27:16][10:0], and its x and y positions defined in the POSX and POSY bit fields DISPC_GFX_POSITION[26:16][10:0]/DISPC_VIDp_POSITION[26:16][10:0]. If there are no graphics or video-encoded pixels at a specific position, the programmable, solid background color appears. The solid background color is set in the DISPC_DEFAULT_COLORo[23:0] DEFAULTCOLOR bit field. Figure 11-75 is an example of priority rule.
The Z-order reordering block must always map the pipelines to the blender logic in the same order—from background to foreground.
The DISPC is capable of outputting simultaniously two graphic/video windows in frame packing mode. Framepacking mode is enabled from DISPC_GFX_ATTRIBUTES[10] FRAMEPACKINGMODE / DISPC_VIDp_ATTRIBUTES[8] FRAMEPACKINGMODE. The position of the second graphic/video windows is defined in DISPC_GFX_POSITION2 / DISPC_VIDp_POSITION2 registers. The size is again defined in SIZEY and SIZEX bit fields of DISPC_GFX_SIZE[27:16][10:0]/ DISPC_VIDp_SIZE[27:16][10:0] registers.