AM625: Enabling 4 Cameras (one chancel per each camera) for CSI-2

Hi Paul,

Looks like you're trying to use each CSI data lane for a different camera. The CSI Rx interface on the AM62x does not support this desing. If you want to run multiple cameras on AM62x, you'll need to use an external CSI aggregator. Please refer to this app note for more details.

Regards,

Jianzhong

Hello Jianzhong

Sorry, I did not provide a complete info.

I reattached all related HW schematics as below, the 4 cameras are the same ( AHD ).

There is a decode/encoder chip in the middle (TP2855). 

Based on my understanding, i need to port TP2855 driver to kernel first.

However, could you provide DTS and guideline for enabling and making these 4 cameras work?

Plus debug guideline. Thanks.

Enable_4Camera_WithTP2855.pdf

Hi Jianzhong

Thank for providing the reference info. In the given link, it seems it has sensor defined and linked in the DTS.

In my case, it is only TP2855 which is linked to AM62x via ([MIPI_D0P, MIPI_D0N], [MIPI_D1P, MIPI_D1N], [MIPI_D2P, MIPI_D2N], [MIPI_D3P, MIPI_D3N]).

May you provide a dts sample of  [MIPI_D0P, MIPI_D0N] ? share a reference that is closed to my case. Thank you.

Hi Paul,

What does the TP2855 do? Does it multiplex the data from 4 cameras and transmit to AM62x via the CSI interface? Please note that AM62x CSI interface doesn't support using 4 lanes for 4 sensors, with one lane for each sensor.

Regards,

Jianzhong

Hello Jianzhong

TP2855 is a video deconder that support simultaneouse 4 channels dec0ding from 4 cameras.

It stand between the 4 cameras and AM62x CSI-2.

As in the attached "Enable_4Camera_WithTP2855.pdf", the connection interfaces are:

1) Camera [4 Cameras , NTSC format] connects to TP2855 via VIN1N, VIN2N, VIN3N, , VIN4N channel

2) TP2855 decodes each input channel to MIPI_D0P/N  ,MIPI_D1P/N, MIPI_D2P/N, and MIPI_D3P/N respectively. 

3) TP2855 to AM62x CSI-2 

   MIPI_D0P/N connects to AM62x CSI-2 [EDGE_CSI0_RXP0, EDGE_CSI0_RXN0]

    MIPI_D1P/N connects to AM62x CSI-2 [EDGE_CSI0_RXP1, EDGE_CSI0_RXN1]

    MIPI_D1P/N connects to AM62x CSI-2 [EDGE_CSI0_RXP2, EDGE_CSI0_RXN2]

    MIPI_D1P/N connects to AM62x CSI-2 [EDGE_CSI0_RXP3, EDGE_CSI0_RXN3] 

We need to define device tree for 3) to get it work. Please help.

Hello Paul,

Thanks for the additional information. Like I said earlier, this case where each data lane is used for a separate sensor is not supported on AM62x.

Regards,

Jianzhong

Hello Jianzhong

I attached our HW schematic (TP2855 connection interfaces with AM62x SOC, tp2855_am62x.pdf) again.

Since  AM62x CSI-2 has 4 lanes, we want to assign each lance per camera, which their connection interfaces are described in 3) previousely. 

"Does it multiplex the data from 4 cameras and transmit to AM62x via the CSI interface?"

=> No, the 4 cameras input (analog) will pass throught TP2855 with diff channels, and TP2855 decodes each camera input saperatly and outputs (digital) them to 4 saperated diff lances (one lane per one camera) to CSI-2 of AM62x. 

Our archecture is similiar to: https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/833182/awr1243-mipi-csi2-format-of-4-lane-from-awr1243

"this case where each data lane is used for a separate sensor is not supported on AM62x."

=> AM62x support only one camera using 4-lane? if we use multiple cameras, we must multiplex the cameras? If so, please provide technical guide how to make it work. Thanks.

tp2855_am62x.pdf

Hello Jianzhong

Thank for your clarification.

1) Our custom board design,  we refer to E3 HW schematic.

In E3 (J19), we see two cameras are connected. There is an  external CSI-2 aggregating component  to combine the two camera output streams and send out an interleaved CSI-2 stream to AM62x's SOC CSI-2?

Originally we thought there is a pin-to-pin between a camera to soc' CSI-2 lane.

2) In our case, suppose that the TP2855 decoder chip could output an interleaved CSI-2 stream of 4 cameras (TP2855 acts as xternal CSI-2 aggregating component), May you guide device tree nodes in order to view the 4 cameras saperatly at AM62x? Thanks.

FYI, TP2855 use MIPI VIrtual Channel output.

Paul Minh said:

There is an  external CSI-2 aggregating component  to combine the two camera output streams and send out an interleaved CSI-2 stream to AM62x's SOC CSI-2?

Yes, that's correct.

Paul Minh said:

In our case, suppose that the TP2855 decoder chip could output an interleaved CSI-2 stream of 4 cameras (TP2855 acts as xternal CSI-2 aggregating component), May you guide device tree nodes in order to view the 4 cameras saperatly at AM62x?

If the TP2855 uses virtual channels to send multiplexed (interleaved) 4 CSI-2 camera streams, this should work. Please refer to the ds90ub960.c and imx219 dtso files I provided earlier.

In addition, please check this app note on multi-cameras using AM6x.

Regards,

Jianzhong

Hello Jianzhong

We face difficulty to define the device tree nodes of AM62x connecting to TP2855.

1) For TP2855, we will write i2c device driver to initial register setup of 4 input cameras and output multiplexed (interleaved) 4 CSI-2 camera streams to AM62x

2) Now, we need to dts nodes which is interface between TP2855's CSI-2 and  AM62x's CSI-2

May you help ?

Hi Paul,

Unfortunately we don't support TP2855.

Regards,

Jianzhong