i.MX ProcessorsのトピックLesser frames per second in MIPI frames

Lesser frames per second in MIPI frames

titusstalin — Thu, 06 Apr 2017 06:06:54 GMT

Hello,

Using customized MIPI CSI camera in imx6 board.

I'm trying to capture the frames in 2592x1944@20fps but I'm getting very less FPS speed i.e ~5FPS.

Can you anyone please tell me what could be the problem ?

FYI:

Able to capture the frames 800x600@30FPS

Regards,

Titus S.

Re: Lesser frames per second in MIPI frames

joanxie — Thu, 06 Apr 2017 07:04:55 GMT

try to confirm what data format and data lane you use.

refer to the Reference Manual,

The maximum bandwidth of the interface is as follows:
• 200Mhz for 4 data lanes configuration (800Mbps/lane, 400MByte/sec)
• 187.5Mhz for 3 data lanes configuration (1000Mbps/lane, 375MByte/sec)
• 125Mhz for 2 data lanes configuration (1000Mbps/lane, 250MByte/sec )
• 62.5Mhz for 1 data lane configuration (1000Mbps/lane, 125Mbyte/sec)

for more detailed infomation, pls refer to the chapter 37.1.2.1.1 Camera Ports of Reference Manual.

Re: Lesser frames per second in MIPI frames

titusstalin — Thu, 06 Apr 2017 07:33:32 GMT

Thanks Joan for your reply.

I'm using 4 lanes and RGB888 pixel format (data format)

Running the MIPI CSI camera at 750Mbps (750*4 = 3000Mpbs) and using imx6 quad core which support 3200Mbps and 4 lanes.

What could be the problem ?

Do I need to set any clock settings ?

Also tried 2560x1440@20FPS, still got 5FPS speed.

I've referred below post. He changed some clock settings, but I'm not able find where need to set those things.

https://community.nxp.com/thread/307065#comment-332645

Also referred the below link and didn't able to find.

http://www.nxp.com/assets/documents/data/en/application-notes/AN5305.pdf

Can you please help me on this issue ?

Thanks for your support and greatly appreciated.

Thanks again.

Re: Lesser frames per second in MIPI frames

joanxie — Fri, 07 Apr 2017 07:57:38 GMT

refer to the F = FH * FW * FPS * BI * DF, I think IPU couldn't support 4 lanes RGB888 in 2592X1944@20fps, but 2560x1440@20FPS can, I think you should check the clock, maybe the default clock isn't enough for your case.

for how to change the clock, you can refer to the part

"MIPI DPHY clock should match the camera sensor clock, as the sensor output Differential clock range is from 80Mhz to 1000Mhz ." in the debug doucment, this documenet in the first link you post.

Re: Lesser frames per second in MIPI frames

titusstalin — Tue, 11 Apr 2017 08:05:19 GMT

I have found root cause of the problem.

Its not due to the imx6 host problem but v4l2 GUI applications.

I have measured the interrupt rate and found it fires the interrupt @20FPS but application is not able to do QBUF and DQBUF for the continuous streaming to achieve the higher FPS.

Thus we can close this issue.

Thanks for your support.

Regards,

Titus S.