My design currently uses the Baytrail-I processor (E382x) and we have been struggling with getting GOP mode working in our system.
------------------> VGA (Debug video output)
Baytrail -------------------------> eDP ---> eDP to LVDS Bridge --> LCD (1280 x 800)
A little background on my design/configuration.
- My current design uses an external eDP-LVDS converter.
- Connection between the Baytrail and the eDP-LVDS converter is via DDI0 port in eDP mode. (The eDP-LVDS chip used is from a vendor in the "supported" chipset list)
- Our LCD backlight is controlled via the PWM from DDI0
- Our LCD is connected to the eDP-LVDS chip using LVDS cabling
- Our display is EDID-less.
- We have configured the vbt.bin for EDID-less mode for 1280x800 resolution (Display Panel #14 in BMP tool). I've also tried programming the DTD information without success.
- We also configured the eDP port timing information (e.g. T3, T5 etc) to match that for the LCD without success.
- When powering up our system, nothing is seen during BIOS initialization (no splash screen nor can I see the BIOS Setup menu)
- With VGA port connected, we are able to see the BIOS splash screen and BIOS setup menu on an external VGA monitor.
- We are using IntelGopDriver.efi is version 7.20.1013 from Kit#:107497. Windows OS driver version
- Upon booting to Windows OS (64 bit version of embedded 8 standard), we are able to see video on our LCD screen.
- The LCD works fine in VBIOS mode (i.e. Video can be seen during BIOS and Windows OS)
- The base code for our BIOS is the same as the one used in the Bayley Bay CRB and Valley Island Eval kit (per information provided to me by my BIOS vendor)
- IntelGoptester.efi tool also shows no display detected when it was run.
I have been trying to resolve this problem since June 2015 and so far seems like no solution in sight. I kept getting bounced around by Intel support in my region and the constant "ding-dongs" between Intel support and my BIOS vendor is starting to take a toll on me. Seems like nobody is able to give me a straight answer on how the whole boot up process in GOP mode works, and each party points to the other (typical scenario with development with any third party vendor, unfortunately) as the culprit.
I do not have access to source code for both Intel and BIOS vendor side to delve deeper in the workings myself.
Can anyone help? What is so different between the IntelGopDriver.efi and Windows OS driver from Intel that one works while the other doesn't? Anyone experienced similar issues and managed to resolve it?
Thank you in advance.