Change output resolution with Colibri iMX8X DSI to HDMI adapter

Dear Community,

I do not know if it is the only way to control it, but the display output resolution with weston container can be controlled using a weston.ini section like the following:

[output]
name=HDMI-A-1
mode=1024x600
transform=90
scale=1

Unfortunately this seems not working to change to a different resolution, let’s lay 800x480, on Colibri iMX8X with DSI to HDMI adapter. I do not know how to change mode in that configuration. Does one have to operate at device tree overlay level? (I am using the default colibri-imx8x_dsihdmi_overlay.dtbo).

Currently, the only mode listed in the sysfs is the following:
cat /sys/class/drm/card0-HDMI-A-1/modes
1024x600

How can I set a different resolution with Colibri iMX8X + DSI to HDMI adapter?

Thank you in advance and best regards,

ldvp

Greetings @ldvp,

In general HDMI resolution and display timings are gathered from the EDID information given by that specific display. Meaning that the resolutions available are given by the display itself.

The way you’re trying to change the resolution via the weston.ini is a correct way to do things. We even document this here: https://developer.toradex.com/knowledge-base/display-output-resolution-and-timings-linux#Weston

But, I believe unless the mode is actually defined via the EDID then it probably won’t work. So the first question would be to determine if your HDMI display supports the resolution you’re aiming for. You can determine this with a display utility like xrandr or fbset. These utilities should list all the available modes for the connected display.

In the case the resolution you want is not provided by your display’s EDID, you do have an alternative. You can inject an alternative EDID with the resolution you want: https://developer.toradex.com/knowledge-base/display-output-resolution-and-timings-linux#Injecting_a_Binary_EDID_Blob

Though please note there may be unintended effects from forcing an EDID that did not come from the display.

Best Regards,
Jeremias