1320bfd91SJonathan Neuschäfer.. SPDX-License-Identifier: GPL-2.0 2320bfd91SJonathan Neuschäfer 3320bfd91SJonathan Neuschäfer==== 4320bfd91SJonathan NeuschäferEDID 5320bfd91SJonathan Neuschäfer==== 6320bfd91SJonathan Neuschäfer 7320bfd91SJonathan NeuschäferIn the good old days when graphics parameters were configured explicitly 8320bfd91SJonathan Neuschäferin a file called xorg.conf, even broken hardware could be managed. 9320bfd91SJonathan Neuschäfer 10320bfd91SJonathan NeuschäferToday, with the advent of Kernel Mode Setting, a graphics board is 11320bfd91SJonathan Neuschäfereither correctly working because all components follow the standards - 12320bfd91SJonathan Neuschäferor the computer is unusable, because the screen remains dark after 13320bfd91SJonathan Neuschäferbooting or it displays the wrong area. Cases when this happens are: 14320bfd91SJonathan Neuschäfer 15320bfd91SJonathan Neuschäfer- The graphics board does not recognize the monitor. 16320bfd91SJonathan Neuschäfer- The graphics board is unable to detect any EDID data. 17320bfd91SJonathan Neuschäfer- The graphics board incorrectly forwards EDID data to the driver. 18320bfd91SJonathan Neuschäfer- The monitor sends no or bogus EDID data. 19320bfd91SJonathan Neuschäfer- A KVM sends its own EDID data instead of querying the connected monitor. 20320bfd91SJonathan Neuschäfer 21320bfd91SJonathan NeuschäferAdding the kernel parameter "nomodeset" helps in most cases, but causes 22320bfd91SJonathan Neuschäferrestrictions later on. 23320bfd91SJonathan Neuschäfer 24320bfd91SJonathan NeuschäferAs a remedy for such situations, the kernel configuration item 25320bfd91SJonathan NeuschäferCONFIG_DRM_LOAD_EDID_FIRMWARE was introduced. It allows to provide an 26320bfd91SJonathan Neuschäferindividually prepared or corrected EDID data set in the /lib/firmware 27*89ac522dSMaxime Riparddirectory from where it is loaded via the firmware interface. 28