Potential violation of the HDMI 12 pixel minimum control period

[hdl-util]

Potential violation of the HDMI 12 pixel minimum control period

[sameer]

If you would be interested in creating a pull request for this, I would be happy to review it 🙂. Otherwise, I'll update the repo at some point.

Let me know how you'd like to proceed. Thanks again for finding this and reporting it

[sameer]

Hi Kris,

Thanks for the detailed report, you're definitely correct. The data island preamble starts prematurely and runs for 8 pixels, when instead it should be delayed by >=4 to get the control period length of 12 pixels.

I'm surprised this has not come up before, maybe most sinks are a little forgiving on this.

There are a few things that need to change:

• data_island_guard (8 to 12, 10 to 14)
• data_island_preamble (0 to 4, 8 to 12)
• data_island_period_instantaneous (10 to 14)
• packet_enable (22 to 18)
• max_num_packets_alongside -- I think this is slightly wrong, too. Need to remove v preamble / d preamble (-16), replace with additional control period (12). There's 4 extra pixels that are not considered

[sameer]

Looking through the issues, this could be the root cause of the issue @mopplayer was having in #35

[krisdover]

Looking through the issues, this could be the root cause of the issue @mopplayer was having in #35

https://imgur.com/ArIkfPk

Yes, I was definitely getting the same 2-pixel white bar to the left of the display as reported in issue #35, that is until I fixed the minimum control period bug.