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jorva
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Contributor
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Registered: ‎01-06-2014

VCU118 pass-through design sink connection difficulty

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Hello,

I ported the KCU105 DisplayPort pass-through design to the VCU118.The validation is being done by adding the VCU118 as an extra sink to my docking station. The screen attached to the VCU118 sink is a Samsung U28E570D.

TX-only (option "t" in main menu) is functional, the image comes on the screen 'immediately'. The resolution can be changed, EDID read out, etc.

Rx seems stable:

  • checksum values seem correct and remain stable
  • when I pass the mouse to this screen (it is configured as an extended screen) the checksum changes

However, the image from the pass-through design only appears on the Samsung screen after multiple (random) startups of the VDMA, each time retriggered by an HPD event as the driver goes through the hpd_con function. Once the image appears, it is stable (video playout runs without a hitch). Choosing 'r' in the main menu seems to lead to more success than 's'...

What could cause this behavior?

Thanks!

 

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jorva
Contributor
Contributor
62 Views
Registered: ‎01-06-2014

The issue seems to be due to the enabling of the TX Buffer Bypass (which was done based on the VCU118 TX only design). When the TX Buffer Bypass is disabled, pass-through works fine on VCU118.

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jorva
Contributor
Contributor
63 Views
Registered: ‎01-06-2014

The issue seems to be due to the enabling of the TX Buffer Bypass (which was done based on the VCU118 TX only design). When the TX Buffer Bypass is disabled, pass-through works fine on VCU118.

View solution in original post