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. CoolStar wish he could've fixed the driver himself but it's closed source so unfortunately that's not an option :/ (CoolStar have experience with writing Windows drivers and have done so to get the other parts of this system working)
CoolStar 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.
Answers (N/A if not applicable)
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.
Brand and Model of the system.
Hybrid or switchable graphics system? ie Does it have AMD or NV graphics too?
No. Integrated only.
Make and model of any Displays that are used to see the issue (see note2 below).
LFP = Local Flat Panel (Laptop panel)
EFP = External Flat Panel (Monitor you plug in)
LFP over eDP
How much memory [RAM] in the system (see note2 below).
4 GB DDR3
Provide any other hardware needed to replicate the issue.
ie: Cables&brand, cable type [vga, hdmi, DP, etc], dock, dongles/adapters, etc
eDP. Internal Display.
Hardware Stepping (see note1 below).
Operating System version (see note2 below).
Windows 10 Pro (Build 10240)
VBIOS (video BIOS) version. This can be found in “information page” of CUI (right click on Desktop and select “Graphics Properties”.
Graphics Driver version; for both integrated Intel and 3rd party vendors (see note2 below).
SW/Apps version used to replicate the issue.
Windows 10 Pro
Single display, clone, or extended (see note2 below).
Display resolution & refresh rate setting of each display (see note2 below).
AC or DC mode, i.e. is power cable plugged in or not?
How to repro
Please provide steps to replicate the issue. Thesestepsare very crucial to finding the root cause and fix.
A screenshot to illustrate the issue is a huge plus. Avideo of the failure is even better! Attach to the post or provide the YouTube link.
1. Install the Graphics Driver
3. BIOS and Windows logo show up
4. Black screen after Windows logo goes away
5. Accessing via teamviewer shows no display detected in Intel Graphics control panel
DxDiag.txt.zip 14.1 K