Acer C720 eDP Display Detection issue Windows 8.1/10 Intel HD Graphics

[PSaha1]

I have been having issues with the Intel HD Graphics driver not detecting the eDP Display properly on the Acer C720 with Windows 8.1/10.

With the Microsoft Basic Display Driver (no Intel HD Graphics Driver installed) the system works perfectly with both eDP and HDMI outputs working. However, when the Intel HD Graphics driver (any version) is installed the eDP stops working. When both eDP and HDMI out are connected, there's lines on both screens. With eDP disconnected and HDMI out connected, the HDMI display works perfectly, indicating it is not a problem with the BIOS but is rather an eDP display detection issue with the Intel HD Graphics Driver.

One thing that I noticed was interesting was that when the Windows 8.1 driver (version 10.18.10.4226) is installed, and Intel HD Graphics is disabled and enabled again from device manager, the eDP turns on and both eDP and HDMI out work perfectly with graphics acceleration until the device is rebooted. this means that it's a detection issue with Intel HD Graphics on the first boot.

In Linux, i915 is able to run both displays properly, it is Windows that has the issue except with the combination of the Windows 8.1 driver and the disable/re-enable workaround. I wish I could've fixed the driver myself but it's closed source so unfortunately that's not an option 😕 (I have experience with writing Windows drivers and have done so to get the other parts of this system working)

I have looked through all the intel documentation and fixed up the coreboot bios and checked the options set in the video bios (version 2170 HSW) and it seems fine and the display does work properly until the Intel HD Graphics driver is loaded.

I have attached the relevant diagnostic information from the Intel HD Graphics although the Intel HD Graphics report is in the "working state" with the older driver + workaround as the control panel crashes when the driver can't detect a monitor connected.

Category

Questions

Answers (N/A if not applicable)

Description

Provide a detailed description of the issue AND 'does it fail every single time, or only sometimes?' If you can offer a % rate please do.

Black Screen After Graphics Driver Installed and after reboot. Fails to turn on display 100% of the time.

Hardware (HW)

Brand and Model of the system.

Acer C720

Hybrid or switchable graphics system? ie Does it have AMD or NV graphics too?

No. Integrated only.

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[Allan_J_Intel1]

I still do not have any word from engineering, Updates are posted as they become available.

Allan.

[PSaha1]

It appears the issue was an incompatibility between the coreboot BIOS and the graphics driver. After updating the BIOS the issue has been resolved...

When patching the BIOS, lines 349 to 355 in here had to be commented out: https://github.com/coreboot/coreboot/blob/master/src/southbridge/intel/lynxpoint/lpc.c# L349 coreboot/lpc.c at master · coreboot/coreboot · GitHub

[Allan_J_Intel1]

coolstar Can you post your current graphics driver version? The driver version may help others with same issue.

Allan.

[PSaha1]

after the BIOS patch, all graphics driver versions started working and detecting the eDP properly. I'm now on the latest 20.19.15.4352 driver (12/15/2015) on Windows 10 Pro Build 10586.

[Allan_J_Intel1]

Thank you for sharing this information. I am sure this will help others on the community.

Allan.