Kernel mode setting

Kernel mode setting (KMS) is a method to set the display resolution in the Linux kernel during boot up, this method also effectly work when:

• you want to set the display mode with specific resolution
• the display device is old
• EDID data is corrupted or it contains incorrect one

Prerequisites

EDID binary

You need to download and install the EDID binary file to your Linux. Please open the link to find out the supported EDID binaries. https://github.com/akatrevorjay/edid-generator

Please run these commands to download the display resolution for 1920x1080.

$ sudo mkdir -p /usr/lib/firmware/edid/
$ sudo wget https://github.com/akatrevorjay/edid-generator/blob/master/1920x1080.bin -P /usr/lib/firmware/edid

Apply new resolution

In order to apply the new display resolution with this method, the boot script must be updated with a kernel parameter that specify the display resoltuion so that the Linux kernel loads the EDID binary on booting.

Add this line to /usr/share/flash-kernel/ubootenv.d/upstream/90-misc to select the display resolution as 1920x1080.

setenv bootargs "${bootargs} drm_kms_helper.edid_firmware=HDMI-A-1:edid/1920x1080.bin"

So, the file /usr/share/flash-kernel/ubootenv.d/upstream/90-misc must be like this.

$ cat /usr/share/flash-kernel/ubootenv.d/upstream/90-misc 
setenv bootargs "${bootargs} cma=800M"
setenv bootargs "${bootargs} clk_ignore_unused"
setenv bootargs "${bootargs} drm_kms_helper.edid_firmware=HDMI-A-1:edid/1920x1080.bin"

Then update the boot script to apply the change and reboot.

$ sudo update-bootscript
$ sudo reboot