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+ Devicetree (DT) ABI
+
+I. Regarding stable bindings/ABI, we quote from the 2013 ARM mini-summit
+ summary document:
+
+ "That still leaves the question of, what does a stable binding look
+ like? Certainly a stable binding means that a newer kernel will not
+ break on an older device tree, but that doesn't mean the binding is
+ frozen for all time. Grant said there are ways to change bindings that
+ don't result in breakage. For instance, if a new property is added,
+ then default to the previous behaviour if it is missing. If a binding
+ truly needs an incompatible change, then change the compatible string
+ at the same time. The driver can bind against both the old and the
+ new. These guidelines aren't new, but they desperately need to be
+ documented."
+
+II. General binding rules
+
+ 1) Maintainers, don't let perfect be the enemy of good. Don't hold up a
+ binding because it isn't perfect.
+
+ 2) Use specific compatible strings so that if we need to add a feature (DMA)
+ in the future, we can create a new compatible string. See I.
+
+ 3) Bindings can be augmented, but the driver shouldn't break when given
+ the old binding. ie. add additional properties, but don't change the
+ meaning of an existing property. For drivers, default to the original
+ behaviour when a newly added property is missing.
+
+ 4) Don't submit bindings for staging or unstable. That will be decided by
+ the devicetree maintainers *after* discussion on the mailinglist.
+
+III. Notes
+
+ 1) This document is intended as a general familiarization with the process as
+ decided at the 2013 Kernel Summit. When in doubt, the current word of the
+ devicetree maintainers overrules this document. In that situation, a patch
+ updating this document would be appreciated.

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