> -----Original Message----- > From: > [email protected] labs.org [mailto:devicetree-discuss-> [email protected]] On > Behalf Of Segher Boessenkool > Sent: Tuesday, January 12, 2010 12:18 PM > To: Yoder Stuart-B08248 > Cc: [email protected]; [email protected] > Subject: Re: RFC: proposal to extend the open-pic interrupt > specifier definition > > > The current open-pic binding defines that interrupt specifiers > > have 2 cells-- an interrupt number and level/sense encoding. > > > > With chips like the P4080 this is no longer sufficient to > > represent the various types of interrupt sources handled by > > the interrupt controller. A linear list of interrupt numbers > > doesn't handle all interrupt types-- there are at least 4 different > > kinds of interrupts on the P4080. > > > > We have a proposal to extend the open-pic binding in > > a backwards compatible way to encode additional information > > in the level/sense field. > > Why can you not have a particular "compatible" for your device, > i.e. have a new binding for it? Changing the "base" binding is > asking for trouble. > > You can of course base your binding on the openpic one.
Sure we can do that, but it is nice to standardize if possible to avoid gratuitous different solutions solving the same problem. > > The advantage of the above approach is backwards compatibility. > > Existing interrupt specifiers (and device trees) are valid with > > this proposal. > > Actually they're not, like BenH pointed out. The proposal is backwards compatible. An existing interrupt specifier (e.g. interrupts = <24 2>;) retains its exact same meaning. Old device trees do not need to change to comply with the proposal. I'm not directly familiar with the case Ben pointed out, but it sounded like Apple used the 1st cell in some non-standard way. It is true that openpic drivers would need to change to handle the new specifier-- minimally masking the level/sense field to 2 bits. Stuart _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
