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joe306
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Registered: ‎12-07-2018

xdpdma_video_example display resolution

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Hello, I'm running the xdpdma_video_example on a custom board that only have one lane. The trouble I am finding it that I'm not able to run at 1920 x 1080. I can only run at 1280x720.

 

displayport.jpg

When I'm try running at 1920x1080 I only get a blank screen. The program shows success on completion. Any ideas what may be the problem?

 

Thank you.

Joe

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joe306
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Registered: ‎12-07-2018
Your are fast! Thank you very much! I just figured that out. Well you are right, as always I'm sure, my monitor can't support HBR2 single lane.

Thank you very much for all your help. There's so much too learn these days.
Joe

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florentw
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Registered: ‎11-09-2015

Hi @joe306 

  1. Are you sure your monitor can support 1920x1080 at 60Hz ?
  2. Are you sure your monitor can support 5.4Gbps per line? If the maximum resolution of you monitor is 1920x1080 at 60Hz, I am pretty sure you will need 2 lanes to support the resolution as the monitor will probably support 2.7Gbps per line (so 1280*720 at 60 Hz will fit not 1920*1080). AR#71499 can help understanding the BW

Florent
Product Application Engineer - Xilinx Technical Support EMEA
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joe306
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Hello, I can run at 1280x720 using 5.4Gbps without any problems using my custom board.

I'll try using the ZCU104 board with 1920x1080 at 60 and get back with you.

Thank you very much,
Joe
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florentw
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HI @joe306 

Are you sure you are really running 5.4 Gbps?

When you set 5.4Gbps in the application this is the maximum line rate. The training might still happen at 2.7Gbps or 1.64Gbps depending on the sink capabilities.

If 1280x720 is working and not 1920x1080, this is very likely to be the BW issue


Florent
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joe306
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Hello, thank you for responding. Is there a way that I can determine the resolution after training? The program reports success after Training but nothing is displayed when at 1920x1080. The ZCU104/106 use two lanes and I'm using one lane, is there something with using two lanes that can do the training and at 1920x1080 and when the monitor fails then the Display Port then runs at 1280x720 at the RBR rate?

Thank you very much for helping me.

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watari
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Registered: ‎06-16-2013

Hi @joe306 

 

What monitor are you using ?

Also, did you make sure capability of this monitor ?

 

I suspect failure issue on elastic buffer or reproduced sync signal issue on elastic buffer.

 

Best regards,

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joe306
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Hello, thank you for responding to my post. My monitor is a:
https://www.samsung.com/us/computing/monitors/led/samsung-27-curved-led-monitor-lc27f591fdnxza/#specs
It can support 1920x1080p.

How do I troubleshoot elastic buffer?

I'm following the instructions for baremetal single-lane:
https://www.xilinx.com/support/answers/71416.html

Could this lead to an elastic buffer problem?

Thank you very much
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watari
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Registered: ‎06-16-2013

Hi @joe306 

 

According to your information, I'm probably sure this issue is lane issue.

I guess Samsung monitor requires two lane as HBR not HBR2.

Would you make sure it by DPCD value ?

 

Best regards,

florentw
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Registered: ‎11-09-2015

Hi @joe306 

Is there a way that I can determine the resolution after training? The program reports success after Training but nothing is displayed when at 1920x1080.

Training and resolution are 2 different things. Training will decide the line rate support. Then based on the line rate this is up to the application but then it is up to the source to send a resolution which will fit inside the bandwidth you have base on the number of lanes and the line rate.

You can get the lane rate after training if you read in the DP controller register:

 
 

 

The ZCU104/106 use two lanes and I'm using one lane, is there something with using two lanes that can do the training and at 1920x1080 and when the monitor fails then the Display Port then runs at 1280x720 at the RBR rate?

Why don't you want to believe me when I tell you that your monitor only support 2.7Gbps/lane???

So even if you select 5.4Gbps in the application, because the maximum from your monitor is  2.7Gbps/lane the maximum line rate you will have during training is 2.7Gbps/lane... So 1280x760 at 60 Hz can fit in one lane at 2.7Gbps not 1920x1080. You would need 2 lanes at 2.7Gbps/lane.


Florent
Product Application Engineer - Xilinx Technical Support EMEA
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joe306
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Hello, thank you for the information. I don't doubt you at all I only need to convince my boss. Could you tell me how I can read the DP control register? I'll look through the code and see if I see anything. I really do appreciate you helping me and I never mean any disrespect.

Thank you
Joe
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joe306
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I ran the test and set the Link Rate for HBR2 5.4Gbps and at 1280x720 60P and it did show the green bar at the bottom of the display. The test displayed:

 

Display.jpg

But as you say, the monitor could have downshifted to HBR 2.7Gbps, that correct. To really know I need to read the DP Control register.

Why does it say Link rate = 10?

Thank you very much,

Joe

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florentw
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Registered: ‎11-09-2015

HI @joe306 

If line rate is 10 (0xA) then this is 2.7Gbps:

florentw_0-1606924517739.png

 


Florent
Product Application Engineer - Xilinx Technical Support EMEA
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joe306
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Link Rate = 10 is HBR Rate.
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joe306
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Registered: ‎12-07-2018
Your are fast! Thank you very much! I just figured that out. Well you are right, as always I'm sure, my monitor can't support HBR2 single lane.

Thank you very much for all your help. There's so much too learn these days.
Joe

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