Debugging two prallel camera operation on custom board based on SabreSD Imx6q evaluation

[makislivadas]

I have a custom build board based on imx6q SabreSD evaluation kit where I connected two parallel cameras ov5640. The cameras are connected to IPU1 and IPU2. The IPU1 CSI1 connection is same as SabreSD setup and works, however the IPU2 CSI2 connection is not working correctly. I done all the mods to the driver to allow two parallel cameras to work. I can talk to the camera and the driver finds the camera. The camera can be programmed too, and all the clock signals generated by the camera are working same as the camera that is working. However, when I display the camera the output does not look synced, but seems to be data coming from the camera. I am looking from some tips on to how to debug my setup.

[jamesbone]

Do you think you can share your  Gstreamer command that you are using, to review if the framebuffers are correct?, have you try to review if recording in a file the camera is working and the display is the one failing?.

Have a great day,
Jaime

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[makislivadas]

Hi,

I finally found the problem. The problem in this case was a hardware one. Being a custom board the PCB layout for the second camera had longer links. After some checking realised that the 56mhz pixel clock signal was not going to the imx6 cleanly so when putting the scope probe to look at the signal the out of sync capture became good. Soldering a small 20pf cap across the pin an the ground near the imx6 fixed the issue.

This is quite good result for me.

There is good advantage from my design as it uses both imx6 ipu's which are not used in the reference SabreSD board which uses one ipu to run two cameras. For me this helps as the IPU_prt_enc driver can be duplicated without BSP code change and can support two cameras concurrently. When one IPU is used this can be achieved with the official BSP only by using IPU_CSI_enc for the second driver. However this driver has less features then IPU_prp_enc driver.

Makis