12-01-2020 07:32 AM
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.
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?
12-02-2020 08:04 AM
12-01-2020 08:02 AM - edited 12-01-2020 08:03 AM
12-01-2020 08:11 AM
12-01-2020 08:19 AM
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
12-01-2020 10:34 AM
12-01-2020 01:26 PM
12-01-2020 01:57 PM
12-01-2020 04:14 PM
12-02-2020 01:36 AM
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.
12-02-2020 06:42 AM
12-02-2020 07:24 AM
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:
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,
12-02-2020 07:55 AM
12-02-2020 08:04 AM