hdmi display shows unexpected black block

[conteczxy]

I am developing on imx6q custom board with android 4.4.2, kernel 3.0.35, the board is connected with hdmi ( 1920x1080M@60 )

I met a problem, when android is running, some black block will show on the screen, its position is uncertain, and its shape is not fixed, some pixel dot or some pixels serial dots will be black.

I exec the screenshot, and the output image is the same as we see on the screen, so I think the hardware is OK. because the graphic framebuffer is also with black block.

Anyone met the same problem?

Any suggestion is appreciated.

Thanks.

The following image is part of screen containing the black block.

[qiang_li-mpu_se]

Since screenshot has the same issue, it should be caused by uplayer code, it is not the low level driver issue.

Maybe you need check your code modification in Android framework to identify which caused the issue.