Usage of GIR mechanism/interrupt in RPMSG operation

[ababatola]

Hi,

I am working on RPMSG for our custom IMX8MP board and I want ask if there is a means of notifying the Cortex A-53 through an  interrupt that the Cortex M-7 has just sent some data through the RPMSG char driver? Then can a read from user space commence.

At the moment, using a read system call, I can read the data from the user space, however, I want to do this read only when the Cortex A-53 gets an interrrupt.

How can the above the implemented?  Is there an existing example for this?

I read in the AN13400 application report that GIR can be used to send an interrupt based notification to the linux kernel.  Can this be adapted for the above?

Thanks

[AldoG · Accepted solution]

Hello,

We do have a similar use case for this, you may refer to the SDK
boards\evkmimx8mp\demo_apps\sai_low_power_audio

From the README file:
In this demo, A core decoded music data and put it to DDR buffer and informs M core with the related information.
Then M core will take the ownership of consuming the buffer, it will copy buffer from DDR to TCM, manipulating SDMA to transfer the data to SAI and codec for playback.
It gives DDR and A core opportunity to do power saving for rather long time frame. M core will also take ownership of codec initialization.
SRTM(Simplified Real Time Messaging) protocol is used to communicate between A core and M core.
The protocol provides various commands for A core and M core to communicate with each other.
If there is no audio palyback, M core will enter the STOP mode, and the whole SOC system would enter deep sleep mode(DSM) once A core enter low power status.

Best regards/Saludos,
Aldo.