On 05/09/18 13:12, Rob Herring wrote: > On Tue, Sep 4, 2018 at 11:59 PM Mark Cave-Ayland > <mark.cave-ayland@xxxxxxxxxxxx> wrote: >> >> On 05/09/18 02:55, Frank Rowand wrote: >> >>> On 08/30/18 12:05, Rob Herring wrote: >>>> Only some old OpenFirmware implementations rely on default sizes. Any >>>> FDT and modern implementation should have explicit properties. Make the >>>> OF_ROOT_NODE_*_CELLS_DEFAULT defines private so we don't get any outside >>>> users. >>>> >>>> This also gets us one step closer to removing the asm/prom.h dependency on >>>> Sparc. >> >> Just for the record: you say "any FDT and modern implementation should >> have explicit properties", however the default values of these >> properties when missing are clearly defined in the IEEE-1275 >> specification (Annex A): > > The spec may define defaults, but best practice is to be explicit. For > FDT, dtc doesn't allow defaults (and never has). No arch added in the > last 10 years has relied on the defaults. > >> "#address-cells" >> Standard property name to define the package’s address format. >> ... >> In a package with a "decode-unit" method, a missing "#address-cells" >> property signifies that the number of >> address cells is two. > > So only Sparc is compliant as the default for everyone else is 1. > >> "#size-cells" >> Standard property name to define the package’s address size format. >> ... >> A missing "#size-cells" property signifies the default value of one. >> >> I can't speak for FDT but it isn't completely unreasonable for a guest >> parsing a DT without these properties to assume these default values. > > I'm not removing the defaults. Just not allowing for code outside of > drivers/of/ to use the defaults. Got it - if dtc requires explicit properties, then I agree there should be no issues with this patch. Sorry for the noise. ATB, Mark.
