SmartDMA documentation for RT595

[jacobvecht]

With the RT595, I need to use DMA to rapidly copy data from FlexIO to a RAM buffer, and the documentation says I should use SmartDMA for this. The RT595 reference manual (Rev 2 of 12/2023) chapter 17 is only one page long and appears to stop abruptly. The majority of the documentation is not there. Where is the documentation for SmartDMA in the RT575? I see NXP has posted the SmartDMA cookbook, and a few very specific app notes. There is also a very minimal API document, clearly also unfinished. I do not see links to any secure document. How do I get a reference-manual level description of this peripheral? 

[jacobvecht]

In summary, NXP has abandoned its users if they want to use FlexIO with any kind of DMA. In that case, NXP should be more straightforward. In the RT595 reference manual Section 51.1.2 (DMA support of flexIO) they should write that there is no support for any DMA for this device since SmartDMA must be used but SmartDMA is undocumented.

Likewise, section 17.2 of the reference manual should be corrected to read "There are 22 external signals associated with the SmartDMA: 22 input/output signals, but NXP has decided not to document these. If you planned to use FlexIO with DMA, your project is toast and you should restart your design with a different processor from a more reputable supplier. 

[Sam_Gao]

Hi,

I also couldn't find information about a public, reference-manual-level details the SmartDMA registers and architecture, here are some comments from the relevant team after double checking:

- The SmartDMA is a programmable coprocessor designed to offload the main Arm processor by handling complex, I/O-driven tasks and data manipulation, which is why it is required for use with the FlexIO peripheral instead of the standard DMA controller.

- Unlike a traditional DMA controller that is configured through registers, the SmartDMA executes a dedicated firmware program to perform its function .The smartDMA driver consists of two parts:
• Configuration and scheduling functions.
• smartDMA firmware program

The execution program flow of smartDMA is as follows:
1. Set the parameters of the specific function of the firmware program to be executed.
2. Call SMARTDMA_Reset() to reset smartDMA.
3. Call SMARTDMA_Boot() to start smartDMA to run the given program based on the API index.
4. After the smartDMA execution is completed, an interrupt signal is generated to notify the Arm core that the execution is completed.

Details in the below AN, section 4.3 SmartDMA overview: Using FlexIO and SmartDMA to Emulate Parallel Camera Interface on i.MX RT500

[jacobvecht]

These general comments posted by @Sam_Gao are once again not a proper response to our question. It is wholly insufficient for an NXP employee to post he cannot find public documentation, as a follow-up to writing a few weeks earlier that he could not find public documentation. What we need is documentation that covers how to use DMA with FlexIO. This presumably means full documentation of SmartDMA. The Application note mentioned is one of those mentioned on a previous post, and we have already said that this is not at all general documentation of SmartDMA. We still have no list of DMA triggers or DMA pacing requests for FlexIO, and not nearly enough information to generate firmware for the SmartDMA coprocessor. 

[Sam_Gao]

@jacobvecht 

Please list exactly what you need.

By publicly available information, I mean information that can be provided to customers; otherwise, it needs to be obtained through special channels, it is out of my scope.

• About ' how to use DMA with FlexIO', I have replied to you multiple times, and there is no further information.
• About ' enough information to generate firmware for the SmartDMA coprocessor.' There is no publicly available information on this part.

Of course, you can also use Professional Support for Processors and Microcontrollers | NXP Semiconductors for suport.

[jacobvecht]

Concerning how to use DMA or SmartDMA to with FlexIO, @Sam_Gao  asked us to list exactly what we need.

We need to know how to trigger DMA or SmartDMA from FlexIO. How do we set up FlexIO as a DMA trigger source or how can DMA transfers be paced from the FlexIO peripheral. 

You say that you have answered my question as to how to use DMA with FlexIO, but you have not. You wrote: 

I couldn't find information about a reference manual containing a complete register map or bit-level programming model for the i.MX RT595 SmartDMA.

When asked why chapter 17 of rev2 of the reference manual for RT595 ends abruptly after just one page your answer was:

This question is out of my scope, and I cannot give a definitive answer. I need to try to find the relevant team and product owner, but I'm not sure if I can, as re-org or unanswerable issues are common

On two occasions you have referred to application notes showing examples that use SmartDMA firmware for very specific use case, but regarding programming SmartDMA for other cases, your response was:

There is no publicly available information on this part.

While we acknowledge that you have provided four answers about publicly available information on this subject, or the lack of such information, the basic question of how to get FlexIO to trigger and pace DMA transfers has not been answered.

[Sam_Gao]

@jacobvecht 

Yes, your description is correct.

Regarding "how to use DMA with FlexIO", only the following publicly available information exists (Reference Manual, Application Notes, API, etc.). Because this IP is undocumented, there are no additional public resources available.

Also, you may also try to seek support from Professional Support for Processors and Microcontrollers | NXP Semiconductors 

But, if your product requires a large volume, you may directly contact the NXP sales team for assistance.

[Sam_Gao]

@jacobvecht 

I couldn't find information about a reference manual containing a complete register map or bit-level programming model for the i.MX RT595 SmartDMA.

The reference-manual level documentation with detailed register maps for the i.MX RT595 SmartDMA is not publicly available, as the intended use is through a high-level API with pre-compiled firmware.

Here is a summary of the available information and the intended usage model based on the documentation:

• SmartDMA API User Guide (IMXRT500SDMAAPIUG): This is the primarysoftware development. It details the API functions used to initialize, control, and interact with the SmartDMA. It includes function prototypes for initialization ( SMARTDMA_Init ), loading firmware ( SMARTDMA_InstallFirmware ), and starting operations ( SMARTDMA_Boot ),
• Application Notes ：AN14650, AN13942, AN14152

[jacobvecht]

This is not a satisfactory solution. I was aware of all these sources before getting your answer, and got almost exactly the same response from you as I previously received from an AI chat bot.  All one can do with these application notes is to make an exact copy of the project described. The API documentation is incomplete, and the chapter on SmartDMA stops mid -sentence after less than one page.  Meanwhile the documentation for the FlexIO says we must use SmartDMA. Nowhere is there any instruction for how to do this unless I want to reproduce the camera examples. We have no list of DMA triggers or request sources. This situation is totally unusable. Here I am midway through a project, the hardware is there and there is no support from the manufacturer ANYWHERE of how to use DMA for a non-standard FlexIO application. This is just too unreasonable. What on earth can I do now? restart the project with an ST microcontroller?  NXP must, MUST provide documentation for the SmartDMA, at the very least, provide a complete API document that lists all the functions and structures, but preferably gives a full list of registers. The present situation is unreasonable and unbearable, and your response is woefully unsatisfactory. At the very least, how does NXP account for the abrupt abandonment of its chapter on SmartDMA in the reference manual?

[Sam_Gao]

'Q1. 'At the very least, how does NXP account for the abrupt abandonment of its chapter on SmartDMA in the reference manual?'

-->This question is out of my scope, and I cannot give a definitive answer. I need to try to find the relevant team and product owner, but I'm not sure if I can, as re-org or unanswerable issues are common.

Q2. The API documentation is incomplete, and the chapter on SmartDMA stops mid -sentence after less than one page. Meanwhile the documentation for the FlexIO says we must use SmartDMA. Nowhere is there any instruction for how to do this unless I want to reproduce the camera examples. We have no list of DMA triggers or request sources. This situation is totally unusable. Here I am midway through a project, the hardware is there and there is no support from the manufacturer ANYWHERE of how to use DMA for a non-standard FlexIO application. This is just too unreasonable.

--> How did you arrive at this conclusion?

[jacobvecht]

Sam_Gao of NXP has asked how I reached the conclusion that "the documentation for the FlexIO says we must use SmartDMA"

My answer is that in the RT595 reference manual rev 2 page 2171 we see the following:

51.1.2 DMA Support
On this device, the standard DMA is not supported for use with the FLEXIO module. The SmartDMA should be used instead. Any reference to the standard DMA should be disregarded in the chapter.