Messages in this thread | | | From | Mark Cave-Ayland <> | Date | Wed, 5 Sep 2018 05:37:32 +0100 | Subject | Re: [PATCH 3/3] of: make default address and size cells sizes private |
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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):
"#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.
"#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.
ATB,
Mark.
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