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Hardware Overlay errors on IMX6Q with Android O8

Question asked by Thomas Elste on Nov 19, 2018
Latest reply on Aug 22, 2019 by Thorsten Wronski

Hi everyone,


on a custom IMX6Q-Board with 4 GB DDR3 RAM running Android O8 we have an issue concerning hardware overlays. Everything seems to work fine. But when starting an application the display shows for 2-3 seconds a greenish kind of pixel mess, which vanishes again, if the application has finished loading:


Overlay Display error on IMX6Q with 4GB RAM


These display errors disappear if I disable overlays (Developer options/Disable HW overlays). Hence why I think it is a hardware overlay issue of the GPU.


DDR3 RAM was calibrated on our board using stress test tool V2.92.


And I found some older thread mentioning a similar behaviour when using more than 2 GB RAM. And indeed overlays work, if I limited the RAM to 2 GB using mem=2GB kernel parameter. As one mentioned solution was to change the GPU base address in the device tree, I checked the current settings. But as far as I can tell the GPU physical base address is already set to the suggested value in the imx6q.dtsi device tree file:


gpu@00130000 {
compatible = "fsl,imx6q-gpu";
reg = <0x00130000 0x4000>, <0x00134000 0x4000>,
<0x02204000 0x4000>, <0x10000000 0x0>,
<0x0 0x8000000>;

Apart from calibration, is there something else, which has to be done when running Android O8 with 4 GB of RAM? Or is there some other way, to avoid this overlay errors?



Best regards