| .. SPDX-License-Identifier: GPL-2.0 |
| |
| ==== |
| EDID |
| ==== |
| |
| In the good old days when graphics parameters were configured explicitly |
| in a file called xorg.conf, even broken hardware could be managed. |
| |
| Today, with the advent of Kernel Mode Setting, a graphics board is |
| either correctly working because all components follow the standards - |
| or the computer is unusable, because the screen remains dark after |
| booting or it displays the wrong area. Cases when this happens are: |
| |
| - The graphics board does not recognize the monitor. |
| - The graphics board is unable to detect any EDID data. |
| - The graphics board incorrectly forwards EDID data to the driver. |
| - The monitor sends no or bogus EDID data. |
| - A KVM sends its own EDID data instead of querying the connected monitor. |
| |
| Adding the kernel parameter "nomodeset" helps in most cases, but causes |
| restrictions later on. |
| |
| As a remedy for such situations, the kernel configuration item |
| CONFIG_DRM_LOAD_EDID_FIRMWARE was introduced. It allows to provide an |
| individually prepared or corrected EDID data set in the /lib/firmware |
| directory from where it is loaded via the firmware interface. |
