IMX8MM Linux: Change Shutdown behaviour

[EmbeddedN00b]

Hi!

I have just started to work in a project where the product uses a imx8m mini module together with Yocto Linux.

Currently we have a problem related to the shutdown behavior of the product, and we need to modify what happens during a shutdown.

As today when we shutdown or a thermal emergency happens,  the PMIC_ON_REQ goes low, but we need to change this behavior that it keeps the current value on PMIC_ON_REQ, as we have other diagnostic devices that needs to talk to the PMIC after that the imx8mm has turned off.

But my current problem is that I don't know where to start, or what kernel module I shall look into.

Does any one have any clue where I shall start to look to be able to find the code for patching?

Please observe that this is my first Yocto project ever, so if I write something strange, bare with me

[jimmychan]

The Linux Yocto BSP documentation could be downloaded from here:

https://www.nxp.com/design/software/embedded-software/i-mx-software/embedded-linux-for-i-mx-applicat...

So, the documents below you may go to read first.

The Yocto Project User's Guide is talking about how to build the BSP in the Linux Host.

The Linux Reference Manual is talking about all the drivers we supported in the BSP.

Also, you may read the Porting Guide about how to put your things into the BSP.

So, you may need to understand the setting in device tree file of your board first. And then you may check the source code in pmic driver, thermal driver or watchdog driver etc.