On Tue, Sep 20, 2011 at 8:49 PM, David Miller <[email protected]> wrote: > From: Rob Herring <[email protected]> > Date: Tue, 20 Sep 2011 15:24:01 -0500 > >> Hopefully, this is the final or near final version of GIC binding support. >> >> Changes from the previous version: >> - SPIs and PPIs are numbered starting at 0. Now the gic has it's own irq >> domain translate function instead of the simple domain one. >> - interrupt cell format has changed based on Grant's proposal. >> - Dropped "ARM: gic: allow irq_start to be 0". Instead, the first 16 irqs >> are skipped and the domain irq_base adjusted accordingly. >> - Added a fix to of_irq_find_parent when the parent == child. >> - Renamed intc_desc.parent to intc_desc.interrupt_parent. >> - Implemented Grant's algorithm for walking the list of interrupt >> controllers. Added a return value to interrupt init functions, so they >> don't get added to the parent list on a init failure. >> >> The changes are significant enough that I did not include previous >> acked/reviewed/tested-by's. > > Just out of curiosity where does this "interrupt-parent" property > come from? > > On platforms I am familiar with, the parent path is walked to the root > and we stop at device nodes that have "interrupt-map" and > "interrupt-map-mask" properties. > > The map and mask are applied to the "reg" property of the device in > question to see which map entry matches, if a match is found the map > entry contains the translated interrupt. > > And this process continues over and over all the way to the root to get > the system interrupt that processor actually deals with. > > The mechanism shown here seems overly simplistic and not able to handle > the cases handled by existing OF property schemes in use for several > years on real systems.
interrupt-parent has been implemented for years on powerpc. I don't know if it was ever an Open Firmware thing, but it is in ePAPR [1], and ARM isn't doing anything novel in that regard. [1] section 2.4, page 30, https://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.1.pdf It is true that is cannot handle all situations, but for those interrupt-map is still available. g. _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
