i.MX8QM LPDDR4 800MHz V4L2 Capture

[hsaito]

Hi,

I have a custom board with iMX8QM running Linux 4.19.35 at DDR4 speed 800MHz.
Here, I have a 60fps camera (NTSC interlaced) via MIPI.
When running in a 65 degree environment, the camera image may freeze.
The software is in normal operation and a fixed image is in the V4L2 buffer.

Are there any possible factors?

At this time, he uses the buffer obtained by g2d_alloc as his V4L2_MEMORY_USERPTR for the V4L2 buffer.
It does not occur when using V4L2_MEMORY_MMAP.
Also, this phenomenon does not occur with the DDR4 1.6GHz setting.

Thanks.

[joanxie]

could you reproduce this issue on nxp mek board?

[hsaito]

Hi,

In the custom board, the NTSC camera is connected to TP2855 and input to MIPI of i.MX8QM.
There is no environment that allows TP2855 to be connected to the MIPI connector of the nxp mek board, so I cannot confirm it.

Thanks.

[joanxie]

it seems higher temperature cause lower bandwidth, the mmap can save cpu usage, so I suggest that you can test lower frame rate or use mmap to improve performance, if you use gstreamera, you also can use dmabuf, add io-mode=dmabuf in the pipeline, dmabuf has higher performance than mmap