I am developing a board which converts DisplayPort to LVDS. The LVDS is put through a PCIe switch and then fed to an APIX transmitter, which connects to the display.
There's a second video path going to this PCIe switch. If this path is active, I get a perfect image in the display.
That video shows what I just wrote, starting with a nice image it gets really bad when I change to the DP source.
I think I have two seperate problems here. One is responsible for the "fringing" or jittering lines, and the other is responsible for the DP image being a few centimeters to the left and cut off. My main concern is the jitter, I think the position of the image can be adjusted by playing with parameters like front and back porch.
Here's a detailed view of my issue:
The position of a view pixels seem to "jump around". The lines are ok and at their correct positions, but sometimes a line is longer than it's supposed to be and fringes appear to the right of the image.
Where shoud I start debugging this problem?
The PTN3460 is set to single LVDS, single DP lane, the resolution is 1280x480 at 60Hz. I also used these parameters:
- pixel clock 40500Hz
- hor active 1280
- ver active 480
- hsync width 15
- vsync width 1
- hblank width 86
- vblank width 14
- hpol neg
- vpol neg
- htotal 1366
- vtotal 494
I also have these:
- hblank start 1350
- vblank start 480
But I am not sure what to do with them, because I am using the "EDID Generator" from analog devices to generate an EDID file. That EDID Generator is asking for:
I am not sure what to do with hor/ver sync offset and hor/ver border, and the unused hor/ver blank parameters, though.
I got the values from the machine that creates the working video output, shown in my first video, the one with the huge tiles.
There's another (commercial) board available, using the exact same EDID I get a clean image. The major difference between their board and mine is: They use HDMI, I use DP.
Where would I start debugging this thing? I have an oscilloscope with 2GS/s and 200MHz max, and a multimeter available.