I am really sorry that @jaski.tx was unable to get you on the right track. Let me try to emphasise a few points.
I have read a lot of your articles, but I am only more confused at a new level…
I assume you also had a look at the following article on our developer website which should really cover it all nicely:
Simple question: In order to change display resolution on the Linux system, do I need to recompile anything, e.g. U-Boot ?
No, usually this is not required. However, ultimately this may depend on your particular display in question and how it physically is connected.
Or is there one text based config file I can change ??
No, in most cases it is enough to adjust the vidargs e.g. from within U-Boot.
I have looked at /etc/X11/x-server-common where there are many lines with " -screen 480x640" and I have tried to change to " -screen 480x800" but no luck…
I have not heard of that file before but do also not think that it helps you in any way solving your issue.
Well, this depends on the type of screen and the interface you are using to connect the screen for display and touch device. In our articles, we have written about the displays we have tested successfully and the ones we are selling, we listed them in the device tree.
Actually, for the Colibri iMX6 this is not quite true as it only features parallel RGB as well as DVI-D aka HDMI. The former may be configured via vidargs and the later will do DDC/EDID by default.
So if you want to have proper working solution during uboot, then the best idea is to put the correct settings in the device tree and uboot settings.
During U-Boot that would be a completely different story but usually, no frame buffer in the boot loader is required. As for the device tree that is really rarely required.
If you just need a correct setting during linux, you can use tools like xrandr to setup the resolution you want.
No, xrandr may only be used to select between available DVI-D aka HDMI resolutions which previously got negotiated using DDC/EDID. Any other use of xrandr is usually not adviced.
Is there a command to reveal versions of HW and SW ? Some info is flashing by on the screen during boot…
root@colibri-imx6:~# cat /proc/device-tree/toradex,product-id; echo
root@colibri-imx6:~# cat /proc/device-tree/toradex,board-rev; echo
I would really assume that just setting vidargs within U-Boot as follows should get you going:
Colibri iMX6 # setenv vidargs video=mxcfb0:dev=lcd,800x480M@60,if=RGB666 video=mxcfb1:off fbmem=8M