4K monitors?

[poma]

...
> https://www.kernel.org/doc/Documentation/kernel-parameters.txt
> drm_kms_helper.edid_firmware=[<connector>:]<file>
> 		Broken monitors, graphic adapters and KVMs may
> 		send no or incorrect EDID data sets. This parameter
> 		allows to specify an EDID data set in the
> 		/lib/firmware directory that is used instead.
> 		Generic built-in EDID data sets are used, if one of
> 		edid/1024x768.bin, edid/1280x1024.bin,
> 		edid/1680x1050.bin, or edid/1920x1080.bin is given
> 		and no file with the same name exists. Details and
> 		instructions how to build your own EDID data are
> 		available in Documentation/EDID/HOWTO.txt. An EDID
> 		data set will only be used for a particular connector,
> 		if its name and a colon are prepended to the EDID
> 		name.
>
> https://www.kernel.org/doc/Documentation/EDID/HOWTO.txt


Also, this can be achieved via 'udev' - Dynamic device management

$ cat /etc/udev/rules.d/69-edid-swap.rules
#  This is a custom udev rule which engages an EDID swap after the device is added.
#
# VGA compatible controller
ACTION=="add", ATTRS{vendor}=="0x1234", ATTRS{device}=="0xabcd", RUN+="/bin/sh -c '/bin/echo DVI-I-1:edid/1920x1080.bin > /sys/module/drm_kms_helper/parameters/edid_firmware'"
#
# udevadm info -a -p /sys/class/drm/card0


$ ls /lib/firmware/edid/1920x1080.bin
ls: cannot access /lib/firmware/edid/1920x1080.bin: No such file or directory


$ dmesg
[drm] Got built-in EDID base block and 0 extensions from "edid/1920x1080.bin" for connector "DVI-I-1"


$ cat /sys/module/drm_kms_helper/parameters/edid_firmware
DVI-I-1:edid/1920x1080.bin


$ monitor-parse-edid /sys/class/drm/card0-DVI-I-1/edid
Name: Linux FHD
EDID version: 1.3
EDID extension blocks: 0
Screen size: 50.0 cm x 28.1 cm (22.58 inches, aspect ratio 16/9 = 1.78)
Gamma: 2.2
Analog signal
Max video bandwidth: 150 MHz

	HorizSync 66-68
	VertRefresh 59-61

	# Monitor preferred modeline (60.0 Hz vsync, 67.5 kHz hsync, ratio 16/9, 97 dpi)
	ModeLine "1920x1080" 148.5 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync


$ monitor-edid
Name: Linux FHD
EDID version: 1.3
EDID extension blocks: 0
Screen size: 50.0 cm x 28.1 cm (22.58 inches, aspect ratio 16/9 = 1.78)
Gamma: 2.2
Analog signal
Max video bandwidth: 150 MHz

	HorizSync 66-68
	VertRefresh 59-61

	# Monitor preferred modeline (60.0 Hz vsync, 67.5 kHz hsync, ratio 16/9, 97 dpi)
	ModeLine "1920x1080" 148.5 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync


$ xrandr --prop | monitor-parse-edid
Name: Linux FHD
EDID version: 1.3
EDID extension blocks: 0
Screen size: 50.0 cm x 28.1 cm (22.58 inches, aspect ratio 16/9 = 1.78)
Gamma: 2.2
Analog signal
Max video bandwidth: 150 MHz

	HorizSync 66-68
	VertRefresh 59-61

	# Monitor preferred modeline (60.0 Hz vsync, 67.5 kHz hsync, ratio 16/9, 97 dpi)
	ModeLine "1920x1080" 148.5 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync


$ monitor-parse-edid /var/log/Xorg.0.log
Name: Linux FHD
EDID version: 1.3
EDID extension blocks: 0
Screen size: 50.0 cm x 28.1 cm (22.58 inches, aspect ratio 16/9 = 1.78)
Gamma: 2.2
Analog signal
Max video bandwidth: 150 MHz

	HorizSync 66-68
	VertRefresh 59-61

	# Monitor preferred modeline (60.0 Hz vsync, 67.5 kHz hsync, ratio 16/9, 97 dpi)
	ModeLine "1920x1080" 148.5 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync


/var/log/Xorg.0.log
...
(II) NOUVEAU(0): EDID vendor "LNX", prod id 0
(II) NOUVEAU(0): Using EDID range info for horizontal sync
(II) NOUVEAU(0): Using EDID range info for vertical refresh
(II) NOUVEAU(0): Printing DDC gathered Modelines:
(II) NOUVEAU(0): Modeline "1920x1080"x0.0  148.50  1920 2008 2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
(II) NOUVEAU(0): Modeline "1920x1080"x60.0  172.80  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz e)
(II) NOUVEAU(0): EDID vendor "LNX", prod id 0
(II) NOUVEAU(0): Using hsync ranges from config file
(II) NOUVEAU(0): Using vrefresh ranges from config file
(II) NOUVEAU(0): Printing DDC gathered Modelines:
(II) NOUVEAU(0): Modeline "1920x1080"x0.0  148.50  1920 2008 2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
(II) NOUVEAU(0): Modeline "1920x1080"x60.0  172.80  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz e)
resize called 1920 1080


poma