I our project we are using the PTN3460i chip for convert the DP to LVDS.
The PTN3460i is connect to a SDM module where there are an Atom X5Z8350.
The connection is all in the PCB, there are no cable.
Our problem is during the BOOT sequence:
Some time it works perfectly and we can see the BIOS screen.
Other times the screen is all red, or blu, or green. Or it turn on slowly with a grey color (attached image).
After the boot sequence, when windows start all works correct!
When windows start there is a IRQ_HPD pulse, and at that moment everything works.
We already worked on the power sequence and the configuration of the chip, but without result.
Any idea why there is this behavior?
Can be a problem during the link training?
The issue picture looks like PC is outputting wrong timing (pixel clock) to PTN3460I during BIOS boot sequence.
Please measure out LVDS pixel clock for good and bad picture during BIOS boot sequence, I am assuming that bad picture should have incorrect LVDS pixel clock (against to LCD panel specification), the issue could be due to DP link training failure or incorrect EDID reading.