Re: [Ksummit-discuss] Devicetree Workshop at Kernel Summit Prague (26 Oct 2017)

[Kumar Gala <kumar.gala@linaro.org>]

> On Oct 17, 2017, at 11:21 AM, Ian Lepore <ian@freebsd.org> wrote:
> 
> On Tue, 2017-10-17 at 14:48 +0100, Grant Likely wrote:
>> On Tue, Oct 17, 2017 at 10:48 AM, Boris Brezillon
>> <boris.brezillon@free-electrons.com> wrote:
>>> 
>>> Hello Grant,
>>> 
>>> On Mon, 9 Oct 2017 21:39:51 +0100
>>> Grant Likely <grant.likely@secretlab.ca> wrote:
>>> 
>>>> 
>>>> Kernel Summit is now just over 2 weeks away and it is time to pull
>>>> together the schedule for the Devicetree workshop. Originally I
>>>> planned on just an afternoon, but I've got the room for the whole day,
>>>> so I've got a lot of flexibility on the schedule. Unscheduled time can
>>>> be used for hacking.
>>>> 
>>>> Date: 26 Oct 2017
>>>> Time: 9:00am-5:30pm (Lunch from 12:30-2:30)
>>>> Location: Athens room - Hilton Prague
>>>> 
>>>> If you plan to attend, make sure you update your OSSunmitE/ELCE
>>>> registration to include the DT Workshop (log in to access and modify
>>>> your registration):
>>>> 
>>>> https://www.regonline.com/register/login.aspx?eventID=1883377&MethodId=0&EventsessionId=&Email_Address=&membershipID=
>>>> 
>>>> Here is my current list of topics in no particular order, including
>>>> the topic moderator:
>>>> 
>>>> Runtime memory consumption (Rob Herring)
>>>> Overlay maintenance plan (TBC)
>>>> Stable ABI for devicetree (TBC)
>>>> DT YAML encoding (Pantelis Antoniou)
>>>> DT Schema format - option 1 (Pantelis Antoniou)
>>>> DT Schema format - option 2 (Grant Likely)
>>>> Sharing Generic bindings (TBC)
>>>> devicetree.org update (Grant)
>>>> 
>>>> Reply to this email if you want to propose another topic.
>>> Not sure yet if I'll attend the DT workshop or not, but I thought I
>>> could ask my question here because it might be of interest to someone
>>> else who is attending.
>>> 
>>> What happens when the DT bindings is not documented in Linux but in an
>>> another project because this project was the first to use it.
>>> 
>>> I had the case here http://patchwork.ozlabs.org/patch/810275/, and I'm
>>> not sure what's the policy when this happens. Should we add a file
>>> under Documentation/devicetree/bindings/... that points to the external
>>> doc file, should we duplicate the DT bindings doc in Linux, or should
>>> we just leave the bindings undocumented in the kernel tree?
>> I'm going to add this as a topic. I've got my own opinion, but it
>> would be better to discuss in the room because it affects maintainers.
>> 
>> g.
> 
> 
> I've run into the same thing in FreeBSD.  We use bindings and dts
> files, exacted periodically from the linux tree and imported into ours,
> for all modern arm boards/systems.  Several times I've created drivers
> for small things like i2c RTC chips that aren't supported currently by
> linux, and it's not clear to me that it's even possible to submit
> bindings and dts for them back upstream without also submitting a linux
> driver that uses them (which of course I'm not in a position to do).
> 
> -- Ian

I think this gets to separating bindings from .dts files.  If we had a common place for bindings that are usable by all the various projects that utilize device tree that would help.  Rob’s point about now having linux maintainers of subsystems doing binding reviews is a fair point, because we do need more eyes on bindings.  So I think we need some middle ground here.

I think this also gets to having bindings described in a structured way so they can be utilized for validation of dts files.  We are doing a little of this in Zephyr since we are using a structured binding spec to generate code from .dts (since we don’t utilize a runtime dtb).

- k