TDA4VM: Support on issue about DSI clock lanes - Continue

Hi Loc,

That's surprising. DSI cannot output data without clock and these lines are dedicated lines, so no other components from the SoC can affect clock lane output. Can you please check on the board if anything else is interfering with the board?

Can you please run DSI standalone PDK based test case if possible? In this case, there is no possibility of any component interfering. 

Regards,

Brijesh

HI Brijesh,

I'm now rebuild with the default source code.

Can you please share me how to run the DSI test?

Best regards,

Loc.

Hi LoC, 

Are you using vision apps ie flashing SD card? Then you need to enable DSI output in app_cfg_mcu2_0.h header file. Can you try disabling DP output and enabling DSI output in this file? You should then see some valid data + clock output on DSI.

Regards,

Brijesh

Hi Brijesh,

Brijesh Jadav said:

Then you need to enable DSI output in app_cfg_mcu2_0.h header file. Can you try disabling DP output and enabling DSI output in this file

Yes, that's exactly what I did. But I still cannot measure the clock

I have a question about the clock. Can you share me what is the frequency of the DSI clock? Is it fixed like xxxMhz or it is adjustable? If it is adjustable, can you teach me how to do that, which are condition/parameters I should care, how can I calculate it? 

Thank you.

Best regards,

Loc.

Hi Loc,

In the default example, we are setting lane speed 850 to 970Mbps lane speed and this can be changed. In the API appDctrlSetDsiParamsCmd in the file app_dctrl.c, dsi_params params struct has an variable laneSpeedInKbps, you can change it to required output lane speed. 

Regards,

Brijesh

Hi Brijesh,

Could you please help take a look in our measurement here:

I try 2 measurement with below setup

1. Measure in TI evaluation board (J721EVM)

2. Measure in our custom HW

I use the same software for both measurement with default configuration for DSI display in vision_apps.

As you can see, the waveform is different between 2 HWs.

So can you help me check with 2 question:

1. With these waveforms, can you confirm which one is the correct form for the DSI continuous clock?

2. Do you have any ideas why there is a difference here? Can this is the cause why my GMSL IC cannot detect the DSI clock because the waveform is not correct?

Best regards,

Loc.

Hi Loc,

Well, the output on TDA4VM is tested with one of the SERDES combo, i would says EVM waveforms are from working condition. 

Are there any board differences in terms of DSI output? Can you check if there is any board component differences on DSI path or any interference? 

Also which SDK release are you using? Are you setting DSI output explicitly in control module register? This should have been taken care in the app_ini somewhere. 

Regards,

Brijesh 

Hi Brijesh,

I'm using the SDK8.5 and using the default config for DSI. I just enable the DSI in the vision_apps config. That's all, and using the same software for measurement.

I measure the DSI clock on the SOM CONN3 by connect copper wires here. Just like below image

The only difference, in the board. I think is the DSI in TI Eval board is not connect to any thing while the DSI lines in our board is connect to GMSL IC.

Do you think that could lead to this difference of the waveform?

Best regards,

Loc.

Hi Loc,

Not an expert on board, so can't say from the board perspective. Has this board schematics been reviewed?

Regards,

Brijesh 

Hi Brijesh,

Brijesh Jadav said:

In the default example, we are setting lane speed 850 to 970Mbps lane speed and this can be changed. In the API appDctrlSetDsiParamsCmd in the file app_dctrl.c, dsi_params params struct has an variable laneSpeedInKbps, you can change it to required output lane speed. 

As I understand, this is about the video lane speed. Can you teach me how to calculate the Clock speed base on these value ( The value of DSI clock in Mhz)?

Best regards,

Loc.

Hi Loc,

It is dependent on the output resolution, so width x height x bpp x fps is the total required speed and now just divide this number by number of lanes. 

Regards,

Brijesh