Green dots and lines in LCD display

[yashavanthashet]

Hi,

I am using i.MX8M custom board with android Pie9.0 release.
Here some green dots are observed in display. The green lines are observed more when I play video in LCD. I am using Raydium rm67198 display. (attached image of lcd).

The LCD display worked fine with 4.9.51 Linux release with same display driver.

The same issue is not observed when I play video in HDMI.

Thanks in advance.

Best Regards,
Yashavantha

[yashavanthashet]

Hi,

Regarding above issue, if "disable hw overlays" property is enabled in developer options then the issue will be solved.

Is enabling above property is needed?

Regards,

Yashavantha

[joanxie]

we don't reproduce this issue on the imx8M evk board, what ddr size you use in your own board? this maybe the gpu hardware limitation issue, I got information that GPU hardware has limitation to access the physical memory address > 0x80000000

[yashavanthashet]

We are using 2GB DDR in our board.

Regards,

Yashavantha

[joanxie]

because of gpu limitation, try to change the source code as below:

Kernel: arch/arm/boot/dts/imx6q.dtsi
Modify to following:
linux,cma {
                        compatible = "shared-dma-pool";
                        reusable;
                        alloc-ranges = <0x40000000 0x40000000>;
                        size = <0x40000000>;
                        linux,cma-default;
          };
 It means that CMA address begin from 0x40000000, CMA size is 0x40000000(1GB), 0x40000000 + 0x40000000 = 0x80000000.
Customer can adjust this two values, just make sure that CMA begin and end address < 0x80000000