.. SPDX-License-Identifier: GPL-2.0
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EDID
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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.
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