How to calculate MIPI CSI-2 required operating frequency

[ko-hey]

Hi all

I'm using i.MX6DualLite and have two questions.

Q1:

According to RM, I can calculate in the following way.

In my case, my board will receive 1080p@60fps and its data format is RGB444.

When calculated according to the formula, the required frequency is almost 240MHz.

F = 1920 * 1080 * 60 * 1.35 * 1.5 = 251,942,400Hz ⇒ 240MHz

I couldn't understand whether if i.MX6 can support the frequency.

Is this frequency would be required in each lane ?

If yes, i.MX6DualLite could not support 1080p60 and its data format is RGB444.

Is it correct ?

Q2:

According to Page 2791 of RM, it can be supported as it looks.

Does the description mean that the max frequency is 125MHz at each lane ?

I think the two description is different each other.

Which one is correct ?

Ko-hey

[Yuri]

  The considerations of the first item (Q1) relate to parallel interface,
strictly speaking, they are not suitable for serial MIPI CSI-2.
As for the serial MIPI, for 1, 2 or 3 lanes maximum throughput is 1000 Mbps/lane,
assuming 125 Mbyte/sec. For 4 lanes  - 800Mbps/lane

Have a great day,
Yuri.

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[ko-hey]

Hi Yuri

I understood it isn't suitable for MIPI CSI-2.

So how can I judge the data is supported ?

Is there any formula for judge it ?

As for MIPI speed, I'm planning to use two lanes.

If I use two lanes, the maximum throughput is 2000 Mbps, assuming 125 MByte/s.

In my undesstanding, I can calculate the required througput from following way.

The required throughput = Frame height * Frame width * Frame rate * Blanking intervals * The amount of data per pixel

So when I use 1080p@60fps in RGB444, I need 480 MByte/s.

1920 * 1080 * 60 * 1.35 * 24  = 3,844 Mbit/s ⇒ 480 MByte/s

From the above results, MIPI CSI-2 I/F cannot support 1080p@60fps in RGB444.

Is it correct ?

Ko-hey

[Yuri]

Hello,

  please refer to app note AN5305 "MIPI–CSI2 Peripheral on i.MX6 MPUs".

http://cache.nxp.com/files/32bit/doc/app_note/AN5305.pdf

Regards,

Yuri.

[ko-hey]

Hi Yuri

Thank you.

I'll check it.

Ko-hey

[ko-hey · Accepted solution]

I got answer from following thread.

MIPI-CSI2 Required Operating Frequency Calculation

Ko-hey