On 10/10/2012 8:45 AM, Stephen Warren wrote: > On 10/10/2012 12:23 PM, Mitch Bradley wrote: >> On 10/10/2012 7:09 AM, Rob Herring wrote: >>> On 10/09/2012 04:16 PM, Stephen Warren wrote: >>>> On 10/01/2012 12:39 PM, Jon Loeliger wrote: >>>>>> >>>>>> What more do you think needs discussion re: dtc+cpp? >>>>> >>>>> How not to abuse the ever-loving shit out of it? :-) >>>> >>>> Perhaps we can just handle this through the regular patch review >>>> process; I think it may be difficult to define and agree upon exactly >>>> what "abuse" means ahead of time, but it's probably going to be easy >>>> enough to recognize it when one sees it? >>> >>> Rather than repeating things over and over in reviews, we should >>> document at least rules we can easily agree on and then add to it when >>> people get "creative." Also, I can't keep up with every single binding >>> review as is, and this could just add another level of complexity to the >>> review. A few off the top of my head and from the thread discussion: >>> >>> - Headers must be self contained with no outside (i.e. libc, kernel, >>> etc.) header dependencies. >>> - No kernel kconfig option usage >>> - No gcc built-in define usage >>> - No unused items (i.e. externs, structs, etc.) >>> - No macro concatenation >>> - No macros for strings or property names >> >> Instead of making a bunch of rules about how you can only use a small >> subset of cpp, why not just add a "define name value" command to DTC? > > I implemented a patch to do exactly that, and it was rejected because it > only solved part of the problem (named constants) and not the reset (a > completely generic macro language/... within dtc). The argument was that > defining just the named constant syntax on its own without knowing what > the unspecified future macro language will look like might result in the > named constant syntax not fitting into it. > > That all said, I now think that using cpp is actually a much better > solution that adding yet more dtc-specific syntax. The *huge* benefit > here is that it allows you to share .h files between *.dts and C code, > so you don't have to write out the same set of #defines once in dtc > syntax and once in cpp syntax.
... and it imposes an equally *huge* restriction that you have to restrict the .h file to avoid avoid C constructs. That can be done, but I've personally experienced a lot of headaches when trying to share .h files between different languages. > _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss
