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

Bird, Timothy Tim.Bird at sony.com
Wed Oct 18 17:41:11 UTC 2017



> -----Original Message-----
> From Geert Uytterhoeven on Wednesday, October 18, 2017 6:22 AM
> On Wed, Oct 18, 2017 at 3:18 PM, Alexandre Belloni
> <alexandre.belloni at free-electrons.com> wrote:
> > On 18/10/2017 at 15:59:00 +0300, Pantelis Antoniou wrote:
> >> > On Oct 18, 2017, at 15:14 , Grant Likely <grant.likely at secretlab.ca>
> wrote:
> >> > On Tue, Oct 17, 2017 at 8:03 PM, Bird, Timothy <Tim.Bird at sony.com>
> wrote:
> >> >>> -----Original Message-----
> >> >>> From Geert Uytterhoeven on Tuesday, October 17, 2017 10:24 AM
> >> >>> On Tue, Oct 17, 2017 at 7:02 PM, Kumar Gala
> <kumar.gala at linaro.org> wrote:
> >> >>>> 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).
> >> >>>
> >> >>> So you are basically generating board files from .dts?
> >> >>> (closing the loop ;-)
> >> >>
> >> >> I think we ought to do this on Linux, as a size optimization.
> >> >> -- Tim
> >> >>
> >> >> P.S.  I think I'll leave it ambiguous whether this was meant as a joke or
> not. :-)
> >>
> >> As crazy that sounds it is possible using the YAML bindings, i.e. C structure
> definitions
> >> and fill-up from DT automatically. Whether this is a good idea it’s another
> question :)
> >
> > But that doesn't work with any driver parsing custom properties (using
> > of_property_read_* and the likes). I would very much like to see what
> > are the boot time improvements when doing that ;)
> 
> Unless you override of_property_read_*() to work on the dense C
> structures instead?

Or turn the property reads into macros that then turn into constant declarations inline in the code.
No need stop at dense C structures.  Of course you lose all configuration flexibility at runtime.
But then that's the kind of trade-off one often makes with embedded software, isn't it?
 -- Tim


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