Messages in this thread | | | Date | Mon, 27 Dec 2021 10:04:18 +0000 | From | Marc Zyngier <> | Subject | Re: [RFC PATCH v1 3/4] dt-bindings: interrupt-controller: realtek,rtl-intc: replace irq mapping |
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On Thu, 23 Dec 2021 19:29:23 +0000, Sander Vanheule <sander@svanheule.net> wrote: > > On Thu, 2021-12-23 at 18:00 +0000, Marc Zyngier wrote: > > On Thu, 23 Dec 2021 12:08:33 +0000, > > Sander Vanheule <sander@svanheule.net> wrote: > > > > > > The binding incorrectly specified the "interrupt-map" property should be > > > used, although the use is non-standard. A quirk had to be introduced in > > > commit de4adddcbcc2 ("of/irq: Add a quirk for controllers with their own > > > definition of interrupt-map") to allow the driver to function again. > > > > That's too late. We have released a kernel with this binding, and it > > will live on forever until we totally remove the platform from the > > tree. > > > > DT is an ABI, and only time travel can fix this blunder. > > Taking into account your comments on the previous patch, this change > wouldn't even be required if I correct the mappings for my > devices. But that wouldn't get rid of the assumed mapping between > output lines and parent interrupts.
A driver can always ignore some information from the DT and do its own thing. No sure if that addresses your problem though.
> > To what extent can the binding be updated to get rid of this > assumption? Or would that require a completely new binding?
You can only extend a binding in a two-way fashion: old kernel works with new DT, new kernel works old DT. Which means that in practice, you can only *add* information to the DT, and have reasonable defaults in the driver when you don't find it.
M.
-- Without deviation from the norm, progress is not possible.
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