Hi Grant, et al, Can we get a comment here? On Thu, Jul 31, 2014 at 11:00:01AM -0700, Florian Fainelli wrote: > 2014-06-19 16:33 GMT-07:00 Florian Fainelli <f.fainelli@xxxxxxxxx>: > > In case the Device Tree blob passed by the boot agent supplies both an > > 'interrupts-extended' and an 'interrupts' property in order to allow for > > older kernels to be usable, prefer the new-style 'interrupts-extended' > > property which convey a lot more information. > > > > This allows us to have bootloaders willingly maintaining backwards > > compatibility with older kernels without entirely deprecating the > > 'interrupts' property (although that is a clear violation of the binding > > specified at > > Documentation/devicetree/bindings/interrupt-controller/interrupts.txt) For the patch: Acked-by: Brian Norris <computersforpeace@xxxxxxxxx> I think it is important that a device tree provide some flexibility on kernel versions. We only invented 'interrupts-extended' in Linux 3.13, so it's easy to have device trees that could work only on 3.13+. Typically, we might say that new features require new kernels, but this is a very basic piece of the DT infrastructure. In our case, we have hardware whose basic features can be supported by a single interrupt parent, and so we used the 'interrupts' property pre-3.13. But when we want to add some power management features, there's an additional interrupt parent. Under the current DT binding, we have to switch over to using 'interrupts-extended' exclusively, and thus we must have a completely new DTB for >=3.13, and this DTB no longer works with the old kernels. How's that for DT stability? On the other hand, if we support this precedence concept, then a new DTB can provide both the 'interrupts-extended' and 'interrupts' properties, and thus be compatible with both pre-3.13 and post-<whenever-this-is-accepted> kernels. > Any comments on this? Brian suggested that I update > interrupt-controller/interrupts.txt to specify the look up ordering > change as well. What do you think about the following DT binding doc update to accompany this change? Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx> diff --git a/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt b/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt index 1486497a24c1..ce6a1a072028 100644 --- a/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt +++ b/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt @@ -4,11 +4,13 @@ Specifying interrupt information for devices 1) Interrupt client nodes ------------------------- -Nodes that describe devices which generate interrupts must contain an either an -"interrupts" property or an "interrupts-extended" property. These properties -contain a list of interrupt specifiers, one per output interrupt. The format of -the interrupt specifier is determined by the interrupt controller to which the -interrupts are routed; see section 2 below for details. +Nodes that describe devices which generate interrupts must contain an +"interrupts" property, an "interrupts-extended" property, or both. If both are +present, the latter should take precedence; the former may be provided simply +for compatibility with software that does not recognize the latter. These +properties contain a list of interrupt specifiers, one per output interrupt. The +format of the interrupt specifier is determined by the interrupt controller to +which the interrupts are routed; see section 2 below for details. Example: interrupt-parent = <&intc1>; -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
