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Registered: ‎03-20-2019

CSI2-TX Word Count

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I'm looking for some clarification on the Word Count that is input onto _tuser[63:48] for the CSI2-TX subsystem IP:

    • Is this number of words per line?
    • By word does it actually mean byte?
    • I am planning to use YUV420, 10-bit. So, e.g. for 1920x1080:
      • Odd lines have (1920 * (5/4)) = 2400 Words
      • Even lines have (1920 * 2 * (5/4)) = 4800 Words
      • Is this correct?
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Xilinx Employee
Xilinx Employee
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Registered: ‎03-30-2016

Hello Andy  andy.martin@videon-central.com 


>Is this number of words per line?

Yes, your understanding is correct.

>By word does it actually mean byte?

Yes, your understanding is correct.

> If we use YUV422, 8-bit, 1920x1080:
> Lines have (1920 * 2) = 3840 Words
> Is this correct?

Yes.

>In addition, does the core make decisions based on "Data Type"? It seems I could repackage 10-bit into 8-bit and use the correct Data Type.

Yes, this is also correct.
You could repackage your data and tell MIPI CSII-2 TX that you are sending YUV422-8bit by using DataType=0x1E (or other supported data tyoes).

Please note that YUV420 has a different word per-line for Even and Odd lines. I don't think this is something we have tested before.
You need to test/verify this usecase on your design.


Kind regards
Leo

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Xilinx Employee
Xilinx Employee
169 Views
Registered: ‎03-30-2016

Hello andy.martin@videon-central.com 


Pri_Second_Data_types.png

As mentioned by MIPI CSI-2 spec,
YUV420 is a secondary data types, which unfortunately not supported by MIPI CSI-2 TX Subsystem.

PG260 mentioned a list of unsupported features:
unsupported_tx_feat.png

Please consider to use YUV422 8bit data type instead.

Kind regards
Leo

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129 Views
Registered: ‎03-20-2019

Leo,

That is unfortunate. However, the questions remain:

  • Is this number of words per line?
  • By word does it actually mean byte?
  • If we use YUV422, 8-bit, 1920x1080:
    • Lines have (1920 * 2) = 3840 Words
    • Is this correct?

In addition, does the core make decisions based on "Data Type"? It seems I could repackage 10-bit into 8-bit and use the correct Data Type.

Thanks,
Andy

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Xilinx Employee
Xilinx Employee
97 Views
Registered: ‎03-30-2016

Hello Andy  andy.martin@videon-central.com 


>Is this number of words per line?

Yes, your understanding is correct.

>By word does it actually mean byte?

Yes, your understanding is correct.

> If we use YUV422, 8-bit, 1920x1080:
> Lines have (1920 * 2) = 3840 Words
> Is this correct?

Yes.

>In addition, does the core make decisions based on "Data Type"? It seems I could repackage 10-bit into 8-bit and use the correct Data Type.

Yes, this is also correct.
You could repackage your data and tell MIPI CSII-2 TX that you are sending YUV422-8bit by using DataType=0x1E (or other supported data tyoes).

Please note that YUV420 has a different word per-line for Even and Odd lines. I don't think this is something we have tested before.
You need to test/verify this usecase on your design.


Kind regards
Leo

View solution in original post