GSoC PRU device tree overlay

Vijay Kumar Banerjee vijaykumar9597 at
Mon May 27 10:36:05 UTC 2019

On Mon, May 27, 2019 at 4:00 PM Nils Hölscher <nilhoel1 at> wrote:

> Hi Vijay,
> On Mon, 27 May 2019 at 12:15, Vijay Kumar Banerjee <
> vijaykumar9597 at> wrote:
>> On Mon, May 27, 2019 at 1:24 PM Nils Hölscher <nilhoel1 at> wrote:
>>> Hi,
>>> I tried to rout the PRUs pins via device tree overlay this week.
>>> Sadly I wasn't able to produce results on linux with this method.
>>> Please check my blog post concerning this issue.
>>> It would be great if someone having experience with device tree overlay
>>> could get me some feed back.
>>> I will now move on to setting up RTEMS and porting the drivers.
>>> Hello Nils,
>> I read your blog and had a look at the overlay. From first look at the
>> overlay I noted that you're using `target-path`. I think target-path holds
>> a path string like "/path" instead of a reference to your pruss. Maybe
>> there should be a `target` field and you'll have to seth the target path
>> manually or just remove it if you're not using it.
>> A few pointers that helped me in general, to get an overlay working :
>>  * always check for the -@ option while compiling with dtc
> I am compiling on the bone with: dtc -O dtb -I dts -o
> /lib/firmware/PRU-GPIO-EXAMPLE-00A0.dtbo -b 0 -@ PRU-GPIO-EXAMPLE-00A0.dts
>>  * before applying using a bootscript in u-boot, it might be a good
>>     idea to use the fdtoverlay tool ( in linux host) and apply it on your
>>     host system.
>  * If it applies well, then just decompile the dtb with the
>>     dtc and have a look at the device you were targeting, if your changes
>>     look nice and so far you didn't get any error during the building,
>> open
>>     u-boot and manually apply overlay using `fdt apply`.
>> With a quick look these pointers might be helpful. I'm working on porting
>> the i2c stack from FreeBSD to RTEMS and have used an overlay for the
>> path and compatibility. Hope these pointers were of some help.
>> I can explain any of the points above if they're not clear and you can
>> post
>> the error log here as well ( if you luckily get proper error messages
>> ;-) )
>> Thank you for these helpful notes.
> I will try them this week and report back.
> It would be nice if you could tell me the command you use for decompiling
> the files.
> Just reverse the options in dtc something like :
`dtc -I dtb -O dts -o

> Best,
> Nils
>> Regards,
>> Vijay
>>> Best regards,
>>> Nils Hölscher
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>>> devel at
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