On Wed, Aug 6, 2014 at 11:54 AM, Brian Norris <computersforpeace@xxxxxxxxx> wrote: > 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. "Must have" to enable the new features? I would expect a new kernel and old dtb still works, right? That is the most important compatibility issue to consider. > 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. Yes, this is what should be done. And I don't have any issue marking this for stable if needed. >> 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? For both changes, Acked-by: Rob Herring <robh@xxxxxxxxxx> Can you send a proper patch for the doc change or combine them. Rob > > 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
