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Old 10-12-2015, 03:52 PM   #1
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Registered: Apr 2014
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Custom platform device


I am working on a proprietary prototype hardware, running 3.10-ltsi. My processor is Arm A9 Cortex.

I have a platform device driver to fetch the data from an external IO device, I recently enabled the CONFIG_PCI option in my config, since then the my driver for the external IO device doesnt work.

I have a printk to print when the open is called.

Without CONFIG_PCI, I see my printk in the driver open function gets called if I do, cat /dev/frontIO

With CONFIG_PCI device, upon doing cat /dev/frontIO, all i get is constant prints of "invalidinvalidinvalidinvalid"

Any clues to any one ?
Old 10-15-2015, 09:15 AM   #2
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I believe you haven't offered anywhere near enough information for anyone to assist you.

From what I can tell: You wrote a custom driver, and you have a printk() statement at the module_init, and based on your kernel configuration your driver doesn't get loaded.

Firstly: Is your driver a standalone module, or did you modify the kernel to call your driver? If you modified the kernel to account for your driver, then it does matter what sub-system of code you performed this modification too. Since you specifically identified CONFIG_PCI, then in the kernel and the modules, there should be conditionals related to that definition. I'd check to see if a normal place in the kernel which would load your module now will not run because of your change. Next I'd check to see if things which your module depends upon are no longer present due to your change.

Is "invalidinvalidinvalid" a print string of yours? Have you tried to search code for printk() statements where "invalid" will be output? I'll grant that there are likely many places where this string will show up, but maybe if you search specifically looking for it as part of a printk() or printf() or system log call, and limit to certain sections, you may find the source of it. And also be able to validate it by modifying certain statements and checking to see what modifications end up making it to your system log. And then perhaps you can trace this down further.

Clearly your module is not being loaded, but now you'll need to dig a bit further to determine what is different. Given that you changed CONFIG_PCI, I'd search all code related to that definition and then parry down that search as you classify the results between "possibly meaningful" versus "not a factor".


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