Payload Bandwidth Management - 3.0 English

DisplayPort 1.4 TX Subsystem Product Guide (PG299)

Document ID
PG299
Release Date
2022-05-04
Version
3.0 English

The following steps manage payload bandwidth in the source controller.

  1. Calculate Target_Average_StreamSymbolTimeSlotsPerMTP based on the VESA DisplayPort Standard (VESA website). Program the VC payload size with the calculated Target_Average_StreamSymbolTimeSlotsPerMTP and align it with nearest even boundary.

    For example if the value is 13, program the VC payload size for this particular stream to 14.

  2. The VC payload calculation for (1920x2200) stream, RGB color sampling, 8 Bits Per Color at 5.4 Gb/s, 4 lanes is shown here:

    VC Payload Band width = LINK_RATE × Lane_count × 100 (Table 2-136 in the DisplayPort standard) = 5.4 × 4 × 100 = 2160

    Average Stream symbol Time slot per MTP = (Pixel_rate × Bits_per_pixel/8/VC Payload_Band width) × 64 (Section 2.6.4.3.1 in the DisplayPort standard) = (297 MHz × 24 /8/2160) × 64 = 26.4

    VC Payload Size = 2/4 symbol aligned of (Average Stream symbol Time slot per MTP) = 28

  3. Program the VC Payload table as defined in DPCD standard.
  4. Program the VC Payload table in source controller as defined in registers 12’h0x800 –12’h0x8FC.