edid.rst 1.1 KB

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  1. .. SPDX-License-Identifier: GPL-2.0
  2. ====
  3. EDID
  4. ====
  5. In the good old days when graphics parameters were configured explicitly
  6. in a file called xorg.conf, even broken hardware could be managed.
  7. Today, with the advent of Kernel Mode Setting, a graphics board is
  8. either correctly working because all components follow the standards -
  9. or the computer is unusable, because the screen remains dark after
  10. booting or it displays the wrong area. Cases when this happens are:
  11. - The graphics board does not recognize the monitor.
  12. - The graphics board is unable to detect any EDID data.
  13. - The graphics board incorrectly forwards EDID data to the driver.
  14. - The monitor sends no or bogus EDID data.
  15. - A KVM sends its own EDID data instead of querying the connected monitor.
  16. Adding the kernel parameter "nomodeset" helps in most cases, but causes
  17. restrictions later on.
  18. As a remedy for such situations, the kernel configuration item
  19. CONFIG_DRM_LOAD_EDID_FIRMWARE was introduced. It allows to provide an
  20. individually prepared or corrected EDID data set in the /lib/firmware
  21. directory from where it is loaded via the firmware interface.