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.
Thank you for contacting the Intel Embedded Community.
We have received your consultations and are working to give you an update as soon as possible.
Thanks in advance for your patience and understanding.
Thanks again for contacting the Intel Embedded Community.
Based on the fact that you are using a third party eDP to LVDS converter, we can only suggest some changes on your GOP configuration settings to test different POST mode resolutions within your GOP configuration:
"General Video BIOS Features
- 1. VBIOS POST mode resolution: Selects the initial mode to be set when DOS boots in hex format. This option allows OEMs to select the mode resolution to set when DOS boots.
03h – 720 x 400 x text
12h – 640 x 480 x 4 bpp
13h – 320 x 200 x 8 bpp
30h – 640 x 480 x 8 bpp
32h – 800 x 600 x 8 bpp
34h – 1024 x 768 x 8 bpp
41h – 640 x 480 x 16 bpp
43h – 800 x 600 x 16 bpp
45h – 1024 x 768 x 16 bpp
50h – 640 x 480 x 32 bpp
52h – 800 x 600 x 32 bpp
54h – 1024 x 768 x 32 bpp
Please let us know if this information is useful to you.
Thank you for the reply.
Re: "We suggest you to address this consultation to the eDP converter manufacturer to further help you to solve this inconvenience."
I did discuss the issue with the manufacturer. However we could not find a solution to the issue. Furthermore, from the chip's perspective it does not distinguish between "BIOS mode" vs "Windows mode", hence they put the issue back to CPU side (i.e. BIOS configuration issues). If the configuration works in Windows OS there is no reason to doubt the eDP converter's operation in BIOS mode also.
I tend to agree with the eDP converter manufacturer's argument. To add on, the eDP did assisted in debugging the configuration on their end and the conclusion was there is no configuration issues on their end.
Would you be able to provide any documentation (i.e. DocID) that walks through the entire process of setting up the display interface for GOP mode? As of today I can't seem to get this information (or any description on this process) from my BIOS vendor or my Intel support guy in my region. I kept getting the run-around from both of them (e.g. Each party is indicating the other is doing the EDID reading process when the system is configured for EDID-less operation).
Basically what I am looking for something similar to below, hopefully in a much more detail (just an example. The one below is not an accurate depiction of the process):
1. Configures the relevant DDI interface for operation
2. Load/execute the GOP driver
3. Starts the EDID reading process.
4. Configures the display mode via GOP protocol
5. Show BIOS boot screen
6. Accept Keyboard interrupt and show BIOS setup screen.
P/S: I do have a debug log from the GOP driver if that helps. I've asked questions on the items seen in the debug log without much success in getting an answer from the Intel support channel in my region.
Hello TAI_YEOH ,
Thanks for your reply.
It is important to let you know that the GOP controls graphic resources during POST and BIOS setup, but it is independent of the driver during OS stage.
We hope that this information is useful to you.