access MIPI from both A53 and M4

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access MIPI from both A53 and M4

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野田周作
Contributor I

Dear person in charge,

I have one question about MIPI on i.MX 8M Mini.

Is it possible to access to MIPI from both Cortex-A53 and Cortex-M4?

best regards,

Shu

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野田周作
Contributor I

Hello Diego-san,

I'm sorry for being late.

Thank you for your answer.

We'll try to keep current approach for a while.

thanks and best regards,

Shu

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diegoadrian
NXP Employee
NXP Employee

Hello,

Unfortunately, both cores could not share the MIPI peripheral. This resource is only exclusive by the cortex A53. 

Best regards,

Diego.

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野田周作
Contributor I

Hello Diego-san,

Thank you for your answer.

I would like to understand more and so let me ask again as below.

Is it possible to execute the following steps?

1. prohibit the access to MIPI-CSI from Cortex-A53 side

2.  access to MIPI-CSI from Cortex-M4 side

3. and then, Cortex-M4 is getting image data from CMOS camera via MIPI-CSI

(Just in case, Linux is running on Cortex-A53 and RTOS is running on Cortex-M4)

I think, in above steps, exclusive processing has been considered.

What do you think?

best regards,

Shu

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diegoadrian
NXP Employee
NXP Employee

Hello,

I apologize if I did not make me understand.

What I am trying to say is that the resource of the MIPI-CSI is not accessible for the M4 cortex. This peripheral is only exclusive for the cortex A53. The cortex M4 does not share the resource of the MIPI-CSI with the cortex A53. 

The i.MX8MM was created that the high-speed interfaces like USB, MIPI, VPU, and HDMI were controlled by the cortex A53. The cortex M4 was only created to be used as a real-time processor. I hope I made me understand.

Best regards,

Diego.

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野田周作
Contributor I

Hello diegoadrian

Thanks for your answer.

From what I have seen of the reference manual so far, we have understood that Cortex-M4 can access  the MIPI peripheral and so we decided to develop the MIPI-CSI driver for Cortex-M4 this time.
And then, let me confirm 2 points as below.
1. Is your last answer from specification of "BSP point of view" or "SoC (Hardware) point of view"?
Is it a software restriction or hardware specification?
 
2. Just in case, let me confirm if this answer is NXP's official one.
 
If you have any questions and then please let me know.
best regards,
Shu
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diegoadrian
NXP Employee
NXP Employee

Hello,

According to the block diagram of the product that is inside the reference manual. The MIPI-CSI Pheriheral is not inside of the peripherals that are shared between the cores.

shared peripherals.jpg

However, the M4 cortex could access to the memory map of the mipi-csi peripheral, you can program the registers with the M4 cortex. But we cannot guarantee if the cortex M4 will give you the necessary bandwidth. Furthermore, just to remark that this is also not supported in our BSP.

Best regards,

Diego.

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