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incorrect output video from ADV7626 when the output color depth is set to 10bpp or 12bpp

Question asked by Leonz on Sep 2, 2014
Latest reply on Sep 4, 2014 by Leonz

Hello,

 

I was seeing an video output issue from ADV7626 if its output color depth was set deep color mode (10bpp or 12bpp).  The sink device was reporting unknown video or displaying video with wrong color if I only changed the register 0x4C in Tx map in ADV7626 from 0x04 (8bpp) to 0x05(10bpp) or 0x06(12bpp).  In my board, the upstream chip was ADV7850,  and the source video to the board was 720p@60Hz with the different color depth(8 bpp, 10 bpp or 12 bpp).

 

The video source I used was Quantum Data 780A and it was used as sink device as well. With the source video 720p@60 to the board, the output video was seen correct from QD 780 only when the register 0x4c is set with 0x04 (8 bpp). During the tests, no other register was toughed. (In HDMI RX map, the register 0x40 was using default value 0x00, which the color depth was getting from GCP from data stream.) 

I noticed the upper 4 bits in 0x4C in TX were not documented in ADV7625 manual, but in ADV7511,  0x4C[7:4] was said as Pixel packing phase for deep color conversion and was read only. I saw 0x4c[7:4] was read as 2 when the output video was good, and 0x4C[7:4] was read as 1 when the output video was not good.

 

The hardware connection from ADV7626 was directly connected to HDMI output connector, which was same as our other products using ADV7511. 

 

With ADV7626, I not sure if I left any register behind or configured incorrectly. Following is the register dump of TX  map from ADV 7626 :

     0  1    2  3   4  5   6   7   8   9  A   B  C    D  E  F

0: 00 00 18 00 01 21 B3 00 00 00 01 0E BC 18 01 13

1: 25 37 00 00 00 00 61 00 06 62 04 A8 00 00 1C 84

2: 1C BF 04 AB 1E 70 02 1E 00 00 04 A8 08 12 1B AC

3: 00 00 00 00 00 00 00 00 00 00 00 80 00 00 00 00

4: 81 10 60 7E 79 70 00 00 00 54 80 00 15 11 12 13                    //0x4C=0x15, 10bpp but video was not good in sink device

5: 14 15 02 0D 70 40 A8 00 00 00 00 00 D1 02 00 00

6: 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

7: 01 0A 00 00 00 00 00 00 00 00 00 00 00 00 00 00

8: 7F 55 55 81 81 81 81 00 01 00 00 00 00 00 00 00

9: 00 00 00 00 C6 C0 38 00 00 78 7C 00 82 30 00 00

A: 00 00 00 00 00 00 00 00 00 00 00 20 00 00 00 16

B: 00 00 00 00 00 00 00 00 20 00 70 00 00 00 00 00

C: 00 00 00 00 00 10 16 00 02 03 00 00 00 00 00 00

D: 44 3C 00 06 70 00 02 00 00 00 40 0B 23 48 18 14

E: 90 FC 02 D0 80 00 00 00 F0 20 1D FC 0C 40 40 41

F: 00 01 00 01 00 D4 08 F0 00 4B 05 DC 55 B0 00 EC

 

Your any advice is really appreciated.

 

Thanks a lot!

Leon Z.

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