Display failed to init when PCH soft strap for presence of internal display not present (hardware issue)
Issue:
Display failed to init when PCH soft strap for presence of internal display not present.
(This is an hardware issue detected in some laptops.)
what happened:
Due to this issue, after updating to version 11, the display failed to init, video out was still available via the HDMI port so the user was able to boot the machine with an external display, get the logs for us and flash the test build.
User operating system: Slackware
Logs:
First cbmem logs, still using version 4.11: cbmem-v1.log
Second cbmem logs, using the 4.9 version: cbmem-debug-v2.log
Third cbmem logs, using the debug version: cbmem-v3.log
This is the debug version: https://source.puri.sm/coreboot/utility/raw/debug/coreboot_util.sh -O coreboot_util.sh
User also reported:
although when it boots to Slackware the screen will remain blank until I unlock my LUKS encrypted root partition (with 4.9 I could see the input screen, with 4.11 it's blank, but the keyboard is functional), after which it seems the driver is loaded and the screen comes on.
We told him to do i915.modeset=1
The resolution was:
To provide user a test build which did not check the PCH soft strap for presence of internal display, and to use i915.modeset=1
kernel param
The underlying issue:
In some units that due to a hardware do have the PCH soft strap for presence of internal display not present, display fails to init.
This happens with version 4.11, but not with coreboot 4.9
support ticket reference: 1286