imx8 screen Tearing or Flimmern while running Demo "weston smoke"

[rs_elk]

Hello, 

I met a Display problem when I run "weston smoke" demo in Wayland-Server on my imx8+raspberrypai-Display. However, there is no problem when I start "weston terminal" or "weston flower".

I cannot upload video here. Generally speaking, I see "ghost Image" flashing around the "real smoke", like this:  

Some Information:

* weston.ini:

• shell=kiosk-shell.so
• backend=drm-backend.so

* imx8nd00

I have the following questions:

* How could I describe this problem exactly?

* It is a hardware Problem (display settings in device tree) ?.

* Can I use weston.ini settings to solve this problem? 

Any help would be appreciated. 

[joanxie]

could you reproduce this issue on other display? like HDMI? if yes, pls send the demo or tell me how to reproduce this issue on nxp board, and what bsp version do you use?

[rs_elk]

Hello joanxie,

thank you for your reply.

Currently I also have a LVDS Display, which connected with my board via MIPI2LVDS Bridge. I see the same Problem.

The BSP we currently used is from KARO Electronics: linux-imx_5.15.32_2.0.0
Forked NXP Kernel. https://github.com/karo-electronics/karo-tx-linux/tree/lf-5.15.y-karo.

We tried to get help from KARO. But sofar we get following usefull information:

* They have the same problem

* The problem appears only bei imx8mn, which we used currently.

From the document I see the only different (in the aspect of Display) is that the imx8mn has no 2D-GPU.

[joanxie]

yes, imx8mn doesn't have 2D GPU, if your demo needs to use 2D GPU, this should be failed

[rs_elk]

Hi Joanxie,

I am not very deep in this area and it is sound maybe stupied. But how should I know this demo is for 2D GPU? If there is no 2D GPU, 3D GPU will take over the job of 2D GPU, right?

I need to run Qt6 on this Chips and during that I also see this problem. What should I do to solve this problem?

[joanxie]

2D gpu and 3D gpu did the different job, I don't know what your demo is and couldn't reproduce this on my side, I really couldn't give any proper answer, I think you need consult the KARO, they should help find the root cause, if this issue belongs to gpu performance issue, they can contact nxp and offer more test result

[rs_elk · Accepted solution]

Thank you for your advice. We received a patch from Karo which successfully resolved the issue. Upon reviewing the patch, it appears that the problem was related to DRM-timings.