Frame Rate Problem in IMX8

[vimalan_93]

Hi

I am using IMX8M evk board with the rocko distribution of yacto bsp(kernel version : 4.9.88).

we used the Monochrome image sensor which supports RAW10 format. we configured the sensor at 480MHZ mipi clock for 30fps but we received only 15 fps in imx8.

We probed the mipi lanes and confirmed the sensor output it generate 30fps constantly. we used the following command to check the framerate in IMX8.

    v4l2-ctl --set-fmt-video=width=1600,height=1300,pixelformat=Y10 --stream-mmap

   <<<<<<<<<<<<<<<<< 15.23 fps
   <<<<<<<<<<<<<<< 15.27 fps

Please help me to solve this probelm.

Thanks in advance,

Vimal.

[hiectai]

Hello @vimalan_93 

I also had the same problem. This issue has been resolved?

[vimalan_93]

In addition to that, I have updated my kernel from 4.9.88 to 4.14.78 version. In the latest version the platform driver mx6s_capture.c have enabled the base address switching mode. when it is enabled i always got an BASEADDR_CHHANGE_ERROR.

when i disabled the base address switching mode i can able to receive 15Fps. but i can't able to receive the expected 30fps.

Please describe the base address switching mode and help us to solve the frame rate problem. Looking forward to your reply.

Thanks

Vimal

[vimalan_93]

Hi Joan Xie,

Thanks for your response,

1. Yes, we are using 1600x1300 resolution in 10 bit raw.

2. The 1080P and 1600x1300 both resolution are almost same in size. As you mentioned mipi-csi2 can support upto 1080p@30fps means why i received only 15 fps? what is the problem?

3.As you mentioned "for imx8M mipi csi, the max throughput is 6Gbps" which means that 1.5Gbps per lane is that correct?

In that case our sensor supports only 2 Lane mode so what is maximum fps can able to achieve in 2 lanes with the raw 10bit sensor? 

Theoretical mipi calculation        

mipi clock = (width * height * Bits per pixel * fps)/lanes

                           = (1600*1300*16*30)/2

                           = 476Mhz

So the required mipi csi host clock should be grater than 476Mhz. what is the current host mipi csi clock?

4. How to calculate and set the MIPI-CSI host clock? where we need to change in code?

Your response is really helpful for us

Thanks in advance

Vimal.

[vimalan_93]

In addition to that, when we increased the sensor mipi clock to 800MHZ  for 60 fps the IMX8m is not properly received the frames. the line length of the frames is mismatched with resolution. please help us to resolve those problems.

Thanks,

Vimal.

[joanxie]

what resolution do you use? capture 1600x1300@30fps in 10bits RAW data？for imx8M mipi csi, the max throughput is 6Gbps, for your 10bits raw data, the max pixel clock is 6G/16bits=375M, on the theory, imx8M each mipi csi2 can support up to 1080p@30

[kenizgandhi]

Hello @joanxie , 

I am getting framerate as 28 fps and i want to increase it to 50 or 60 fps. is there any way to do it? I have imx8mp evk board with minisastocsi camera. 

Thanks and Regards,

Keniz