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.