[linux-yocto] Beaglebone Black BSP CAN bus activation

[Bruce Ashfield]

On 15-01-21 03:39 AM, Lukas Böhm wrote:
> Am 20.01.2015 um 16:58 schrieb Bruce Ashfield:
>> On 15-01-16 08:58 AM, Lukas Böhm wrote:
>>> Hello,
>>>
>>> I hope this is the correct destiantion list for Yocto-BSP-Questions.
>>
>> It's a good starting point. General questions for the supported BSPs in
>> linux-yocto tree can typically be answered here .. but if we get into
>> particulars and variants of the boards, there are maintainers and other
>> lists that are better suited.
> Thanks for your answer so far! The next questions are quite general to
> the yocto/oe mechanism.
>>
>>> I am new to Yocto and trying to build a core-image-base (daisy branch)
>>> with some additional packages for the Beaglebone Black. This works quite
>>> fine so far.
>>> Now I stuck in activation of the 2 DCAN controllers on the device.
>>> I added the drivers for DCAN in the linux-yocto kernel (with menuconfig)
>>> and and added iproute2, libsocketcan and canutils to the recipes but no
>>> can0 device comes up.
>>
>> Anything in the dmesg about the device ? Are you building them as
>> modules,
>> or into the kernel ?
> Nothing in dmesg. I build them into the kernel. But I can say it works
> on the official Debian distro with device tree overlays. But I don't
> want to use the cape manager from there but have it running right out of
> the box.

ok. But I suppose that means there may still be kernel differences
that explain the delta .. i.e. we don't have all the patches we need
on the yocto kernel to support it.

>>
>>> I considered now that probably the devicetree has to be configured as
>>> well but don't know how to do this nicely.
>>
>> You can see the device tree that is currently being built in the
>> meta-yocto-bsp beaglebone.conf file. Those dts files are in the kernel
>> themselves, so you can edit them and rebuild .. or patch them to have
>> the missing elements.
>>
> The KERNEL_DEVICETREE variable points to dtb files. Does this mean that
> they are precompiled and I may change them to the dts equivalents
> including my patches? How to rebuild them with bitbake?

It means that there's a .dts in the kernel source that will be built
using the uboot / kernel support, to create the dtb which is then
deployed along side the kernel.

So to change those targets, you can patch the kernel. Or you can provide
your own .dts under another name and have it built.

The dtbs are built via linux-dtb.inc, which is included by the kernel
recipe. They are built and deployed via the install/deploy tasks, so
something like:

   bitbake -f -c install linux-yocto

Should pick up any modified dts files and rebuild them.

Cheers,

Bruce

>
>> It is also worth checking https://github.com/beagleboard/meta-beagleboard
>> for configuration tips, and the mailing list referenced in the README
>> for more detailed questions/information/archived responses.
>>
>> Bruce
>>
>>> Am I right or are ther other things to consider?
>>> I am thankful for any help!
>>>
>>> regards Lukas
>>
>
> regards
> Lukas