How to configure DisplayPort TX to support BT.2020 colorimetry

[petr_simi]

Hi everyone,

we are not able to configure DisplayPort TX to use BT.2020 colorimetry.

Let's say we want to transmit YCbCr 4:2:2, 10 bit, limited range, BT.2020.

According to the DisplayPort 1.4 specification we set MISC0 and MISC1:

 DPTX0_MSA_MISC1

• bit 6 = 1 (Use VSC SDP)

MISC0 should be ignored now, but we still set it, e.g:

DPTX0_MSA_MISC0:

• bits 7-5: 010 (10 bit)
• bit 4: 1
• bit 3: 0
• bit2-1: 01 (4:2:2)

DPTX0_MSA_COLOR:

• bit 13: 1 (use VSC SDP)
• bit 12: 1 (CEA range)
• bits 11-8: 0111 (BT.2020 YCbCr)
• bits 7-4: 0010 (YCbCr 4:2:2)
• bits 2-0: 010 (10 bits)

we also call Bitec function:

btc_dptx_set_color_space(0 /*instance*/, 2 /*YCbCr 422*/, 2 /*10bits*/, 1 /*limited range*/ , 7 /*bt2020*/, 1 /*use VSC SDP*/);

Basic colorimetries (BT609 and BT709) and color spaces (RGB, YCbCr 422/444) works well, when we use MISC0 instead od VSC SDP.

Using Quartus Pro 19.1

Can you please advice how to put BT2020 into operation?

Thank you,

Petr

[Deshi_Intel · Accepted solution]

HI,

You are right in the sense that BT.2020 should be enabled via VSC SDP but I don't see you enable "secondary data channel" in your Intel DP Tx IP.

• This could be the problem as you are transferring secondary data packet (SDP) here

Below is what I found out from DP rev1.4 spec

1. Pre-requisite

• Ensure DP sink EDID support 3D Stereo in-band signaling
  • Ensure DP sink enable “VSC_SDP_EXTENSION_FOR_COLORIMETRY_SUPPORTED”, DPCD address 0x2210h (bit 3 = 1)  
  • Enable Intel DP Tx “secondary data channel”
• Then to enable/configure BT.2020 support
  • DP Tx set MSA (MISC1, bit6 =1) to use VSC SDP
  • Configured YCbCr 422 BT.2020 setting via VSC SDP, payload data byte (DB16)

Thanks.

Regards,

dlim