IMX8MP CSI interface 1080p60 support

[jemish_1990]

Hi All,

We are using IMX8MP (MIMX8ML8DVNLZAB) based board. 

Kernel version: 6.1.55

We are using following setup:

Another board-->DP port video-->Lontium (LT7911d chip)-->MIPI interface-->CSI interface of IMX 

We are using Lontium DP to MIPI converter to capture video. There is one another board which is providing video to DP port. DP to MIPI converter chip is converting video MIPI protocol that we are capturing. 

We observed that we are successfully able to capture 1080p25 but when we change to 1080p60 it doesn't work. Currently to avoid any confusion instead of converting video coming from another board we are sending pattern directly from Lontium (LT7911d) chip. 

We would like to understand is there any limitation with IMX8MP + CSI interface for 1080p60 resolution. Is there anything we need to adjust to capture 1080p60 resolution?

There is one more observation whenever I tried to  read any register of CSI interface I am always getting 0x0 value.  (MIPI_CSI1_CSIS_COMMON_CTRL). 

example:

devmem 0x32e40004 32

0x00000000

This observation is same irrespective of capture is working or not working. 

I am asking this information because we want to provide following information to chip vendor. Are CSI registers responsible for providing following information. 

Horizontal parameters:

• htotal
• hactive
• hfp
• hbp
• hsync

Vertical parameters:

• vtotal
• vactive
• vfp
• vbp
• vsync

Please provide your inputs and suggestions. Any pointers will be appreciated. Currently our project is going through critical phase so any inputs are appreciated. 

Thanks,

Jemish

[joanxie]

do you use mipi csi0 or mipi csi1? and do you use ISI or ISP? do you use only one mipi csi or dual mipi csi?

[jemish_1990]

Hi @joanxie 

Thanks for your response. 

>> do you use mipi csi0 or mipi csi1? <<

We are using mipi csi0

>> and do you use ISI or ISP? <<

We are using ISI.

>> do you use only one mipi csi or dual mipi csi? <<

We are using mipi csi only , not dual MIPI CSI. 

We are facing same issue with 720p60 capture. 

Thanks,

Jemish

[joanxie]

if you just use mipi csi0, can support up to 4k@30, 1080p@60 can be supported without limitation, the default bsp can support this already

[jemish_1990]

Hi @joanxie ,

I understand that from BSP and hardware point of view there no limitation in capturing 1080p60. As I mentioned in previous comment are facing same issue with 720p60 resolution. We are not able to capture 720p60 video pattern sent by DP to MIPI chip (Lontium lt7911d).  Is there anything we can debug or adjust? Are there any CSIS registers that I can print in kernel to identify issue? Any suggestion is appreciated. 

Thanks,

Jemish

[jemish_1990]

Hi @joanxie ,

Any update on this? Currently based on our experiments it seems that we can only capture 1080p25 from DP to MIPI chip. We tried with 720p60 and 720p25 with different format , also tried to capture 1080p60 but can't capture. 

Thanks,

Jemish

[joanxie]

how do you confirm what frame rate you can get? do you use gstreamer or any tools? share your testing steps