There is no need to change it. We look into the code and these pins are already defined as SPI out-of-the-box. So you neither have to touch the kernel nor any other config, for that matter.
The most probable issue here is another one.
Do you have CAN enabled on your device?
I am asking because when CAN is enabled the SPI interface gets assigned a higher chip select number which can prevent a script like “spidev” to work properly. As long as CAN is enabled, this interface will receive the Chipselect 0 and all the SPI interfaces will start from Chip select 1.
If you disable CAN, the SPI interface starts at Chip select 0. With this, it should be possible to run the spidev, without running into issues. So I recommend disabling CAN.
Updating the kernel won’t be an option I fear. There would be loads of changes necessary to achieve anything. Since Nvidia has dropped support for their kernels on T20 a while ago. I suggest to avoid it and trying to add support/ fix the current issue on the kernel you already use.
So how I understand you, the given options based on your recommendation Kevin is, that CAN needs to be disabled only in the Kernel config(s) in order to use the already defined SPI4 interface at the SODIMM pins (86, 88, 90, 92) and there is no need to touch any other souce file, pinmuxings etc.?
I am strongly believing that CAN is enabled because there was no change made from my side to the reference source or even the already built reference image 2.8b7.
However in which Kernel config file I would have to apply the changes, I am not sure.
Could you help me with the /path, the config_file_name and the VARIABLES that has to be adjusted with which values in order to disable CAN?
Yes, that is right. If you did not change anything else, there would be no need to change any pinmuxing etc.
So, if this is the case I recommend trying that approach.
To successfully do this, I recommend giving this article a read. In it all the steps on how to build a new kernel are explained.
Someway down the article you will see the section about kernel configuration. Wo make it easier to navigate, I recommend using “make menuconfig” instead of “make nconfig”.
As soon as you see the UI you can press “/” to open the search field. In this field enter “CAN” and in the results that will pop up you will see a number in brackets. Something like “(1)”, if you then press this number you directly jump to the designated point in the configuration. Then press “n” for disabling it, rebuild the kernel and try again.
