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-:orphan:
-
-====
-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. The code
-(see drivers/gpu/drm/drm_edid_load.c) contains built-in data sets for
-commonly used screen resolutions (800x600, 1024x768, 1280x1024, 1600x1200,
-1680x1050, 1920x1080) as binary blobs, but the kernel source tree does
-not contain code to create these data. In order to elucidate the origin
-of the built-in binary EDID blobs and to facilitate the creation of
-individual data for a specific misbehaving monitor, commented sources
-and a Makefile environment are given here.
-
-To create binary EDID and C source code files from the existing data
-material, simply type "make".
-
-If you want to create your own EDID file, copy the file 1024x768.S,
-replace the settings with your own data and add a new target to the
-Makefile. Please note that the EDID data structure expects the timing
-values in a different way as compared to the standard X11 format.
-
-X11:
- HTimings:
- hdisp hsyncstart hsyncend htotal
- VTimings:
- vdisp vsyncstart vsyncend vtotal
-
-EDID::
-
- #define XPIX hdisp
- #define XBLANK htotal-hdisp
- #define XOFFSET hsyncstart-hdisp
- #define XPULSE hsyncend-hsyncstart
-
- #define YPIX vdisp
- #define YBLANK vtotal-vdisp
- #define YOFFSET vsyncstart-vdisp
- #define YPULSE vsyncend-vsyncstart