Messages in this thread Patch in this message | | | Date | Wed, 6 Aug 2014 09:54:52 -0700 | From | Brian Norris <> | Subject | Re: [PATCH] of/irq: lookup 'interrupts-extended' property first |
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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@gmail.com>: > > 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@gmail.com>
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@gmail.com>
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>;
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