DT include files

On Fri, Jan 10, 2014 at 09:30 -0600, Rob Herring wrote:

As for *.h vs. *.dtsi naming, if the include is only pre-processor
defines, then I think using .h is the right way. Otherwise, if there
is any dts syntax, then .dtsi is the right name. It looks to me like
this style has been followed in both the imx and s3c64xx cases.

On a side note, I'm not really a fan of this pattern:

#define FOO1 1 2 3

#define BAR FOO1 FOO2 FOO3

While it definitely simplifies the dts files, it would never be used
in C and obfuscates what the actual property size is. Reading a dts
file, I would naturally assume the define was a single value while in
fact it could expand to a very large property size.

For more complex yet tedious repetitive cases like GPIO banks and
pins I've seen #define directives which introduce "functions"
(macros with parameters).  They appear to be rather useful, can
reflect very well the essence of the information, don't
necessarily pretend to be single values, but still may hide how
many cells they expand to.  For example:

  arch/arm/boot/dts/tegra30-cardhu.dtsi:
    interrupts = <TEGRA_GPIO(L, 0) IRQ_TYPE_LEVEL_HIGH>;


virtually yours
Gerhard Sittig
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