linux device tree reverse engineering

[Bhargav Jayswal]

Hello sir,

My company does not have documentation of their current project running in the field. I'm trying to reverse engineer the already built system to add new features like enabling CAN and I2C interface in the kernel. I have attached a boot log for your reference and I have a query that  "after disabling the old interface spi0 and spi1 through the device file those interfaces are still available as /dev/spidev1.0 and /dev/spidev1.1  after boot up".

I have also removed all .dtbo overlay files in /lib/firmware. but still i am unable to disable spi interface. Could you please suggest how to debug further and correct the way to go forward to enable CAN interface.

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Thanks and Regards,

Bhargav Jayswal

M: (+91) 9586228800

[Anil Kumar Pugalia]

What do you mean by disabling the interface through device file?

You may also look into the .dtb files by converting them into .dts - just to get more insight.

Regards
Anil

Passion: http://sysplay.in (Playing with Systems)

Bhargav Jayswal wrote on 22/03/22 5:00 pm:

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[Bhargav Jayswal]

Hi Anilsir,

I mean that I have disable SPI interface in the device tree file as attached in the mail. Beagle bone has a concept called CAP-manager which might bring up SPI interface even if we disable it in the dts file.So i was just wondering how SPI is getting up and how my LCD is also getting up without pin mapping in device tree.

Best Regards,

Bhargav Jayswal

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[Anil Kumar Pugalia]

May be it is picking up some other dtb file from somewhere else. Not really sure about the CAP-manager stuff.

Regards
Anil

Passion: http://sysplay.in (Playing with Systems)

Bhargav Jayswal wrote on 23/03/22 12:00 pm:

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[Bhargav Jayswal]

Hello Anil Sir,

I have found out that capmanager is causing an issue, which does not come with the mainline kernel src . It was patched to the mainline kernel externally by some of  x-Employee. Now I am freshly compiling mainline kernel 5.16  without any external pach or packages.

Best Regards,

Bhargav Jayswal

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