The following steps manage payload bandwidth in the source controller.
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Calculate Target_Average_StreamSymbolTimeSlotsPerMTP
based on the DisplayPort Standard v1.2 or later. Program VC payload size with calculated
Target_Average_StreamSymbolTimeSlotsPerMTP and align it with nearest even boundary.
For example if the value is 13, program VC payload size for this particular stream to 14.
- In MST mode when GT data width is 4 bytes the VC Payload should be multiple of 4.
-
The VC payload calculation for (1920x2200) stream, RGB color sampling, 8 Bits Per Color
at 5.4 Gb/s, 4 lanes is given here.
VC Payload Band width = LINK_RATE × Lane_count × 100 (see Table 2-61 in the VESA DisplayPort Standard v1.2a)
= 5.4 × 4 × 100 = 2160
Average Stream symbol Time slot per MTP = (Pixel_rate × Bits_per_pixel/8/VC Payload_Band width) × 64 (see Section 2.6.3.3 in the VESA DisplayPort Standard v1.2a)
= (297 MHz × 24 /8/2160) × 64 = 26.4
VC Payload Size = 2/4 symbol aligned of (Average Stream symbol Time slot per MTP)
= 28
- Program VC Payload table as defined in DPCD standard.
- Program VC Payload table in source controller as defined in registers 12’h0x800 – 12’h0x8FC.