On Tue, Jan 12, 2010 at 11:36 AM, Yoder Stuart-B08248 <[email protected]> wrote: >> > 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.
You also need to deal with the case of old drivers incorrectly binding to and trying to understand the new data. > 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. Which makes the new binding incompatible with old kernels/drivers which just leads to confusion. It's not worth toying with. Just create a new compatible value for this new binding and be done with it. When a driver gets modified to handle the new behaviour, then it can be also changed to bind against the new compatible value too. g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
