topic i.MX8MQ: How to disable zero packing with MIPI CSI2 RGB888 pixel data in i.MX Processors

i.MX8MQ: How to disable zero packing with MIPI CSI2 RGB888 pixel data

tor_wang — Mon, 30 Mar 2020 09:50:26 GMT

Dear NXP member,

We use i.MX8MQ with Linux 4.14.98_2.0.0 BSP.

The original codebase (drivers/media/platform/mxc/capture/mx6s_capture.c) doesn't implement RGB888 format capture.

After adding RGB888 format related code then we can capture RGB888 pixel data, but there exists zero packing.

Try some CSI control registers but in vain, the ZERO_PACK_EN is useless.

Also searching in NXP community, we find out the issue is the same as RGB888 pixel data: disable zero-byte padding?

How to disable zero packing with MIPI CSI2 RGB888 pixel data?

How to configure the correct CSI control register for MIPI CSI2 RGB888 pixel data capture?

Best Regards,

Tor Wang

Re: i.MX8MQ: How to disable zero packing with MIPI CSI2 RGB888 pixel data

joanxie — Sun, 05 Apr 2020 06:14:40 GMT

I got reply:

"ZERO_PACK_EN is only available in 8-bit/pixel mode.

It seems that you can not avoid packing to 32 bits data when you use 24 bits parallel input.

How about cut off the packing 8 bits 0 in application?you may need to configure DMA controller to try 24 bits transition for your requirement.

Re: i.MX8MQ: How to disable zero packing with MIPI CSI2 RGB888 pixel data

tor_wang — Mon, 06 Apr 2020 01:14:35 GMT

Dear Joan,

Thanks for reply about the "ZERO_PACK_EN" CSI control register 3 usage.

Follow your reply:

"you may need to configure DMA controller to try 24 bits transition for your requirement."

=> Please also answer my previous question:

"How to configure the correct CSI control register for MIPI CSI2 RGB888 pixel data capture?"

Best Regards,

Tor Wang

Re: i.MX8MQ: How to disable zero packing with MIPI CSI2 RGB888 pixel data

tor_wang — Mon, 13 Apr 2020 01:05:15 GMT

Dear joanxie & NXP member,

Any updates about the question "How to configure the correct CSI control register for MIPI CSI2 RGB888 pixel data capture?"

Or do I have to create another thread to ask the question above?

Best Regards,

Tor Wang

Re: i.MX8MQ: How to disable zero packing with MIPI CSI2 RGB888 pixel data

joanxie — Mon, 20 Apr 2020 04:27:07 GMT

I have already answered:

"It seems that you can not avoid packing to 32 bits data when you use 24 bits parallel input."

for imx8 side, no register can avoid this, maybe you can try to do this on your application side, I give the advice above.

Re: i.MX8MQ: How to disable zero packing with MIPI CSI2 RGB888 pixel data

tor_wang — Mon, 20 Apr 2020 06:04:52 GMT

Dear Joan,

Thanks for the feedback.

Explain my doubt about your description as below:

The question above I asked is about your description "How about cut off the packing 8 bits 0 in application?you may need to configure DMA controller to try 24 bits transition for your requirement."

=>If I cut the zero packing off on application side, just to use the default DMA controller configuration, no need to do extra DMA controller configuration.

=>So I have to ask the question above again. If I have to do extra DMA controller configuration then please tell me how to configure those registers.

Anyway, thanks for your answer: "for imx8 side, no register can avoid this".

We will cut the zero packing on application side.

Best Regards,

Tor Wang

Re: i.MX8MQ: How to disable zero packing with MIPI CSI2 RGB888 pixel data

joanxie — Mon, 18 May 2020 08:09:32 GMT

what camera do you use, I confirmed that ov5640 couldn't set rgb888