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    SubjectRe: [PATCH 5/5] ARM: gic: add OF based initialization
    On Sun, Sep 18, 2011 at 04:23:40PM -0500, Rob Herring wrote:
    > On 09/15/2011 11:43 AM, Rob Herring wrote:
    > > I see 2 options (besides leaving it as is):
    > >
    > > - Revert back to my previous binding where PPIs are a sub-node and a
    > > different interrupt parent.
    > >
    > > - Use the current binding, but allow SPIs to start at 0. We can still
    > > distinguish PPIs and SPIs by the cpu mask cell. A cpu mask of 0 is a
    > > SPI. If there was ever a reason to have a cpu mask for an SPI, you would
    > > not be able to with this scheme.
    > >
    > > Either way you will still have the above issue with the cell size changing.
    > >
    >
    > I was headed down the path of implementing the 2nd option above, but had
    > a dilemma. What would be the numbering base for PPIs in this case?
    > Should it be 0 in the DT as proposed for SPIs or does it stay at 16?
    > Numbering PPIs at 0 will just cause confusion as will numbering
    > differently from SPIs. There is absolutely no mention of SPI0 or SPIx
    > numbering in the GIC spec. All interrupt number references refer to the
    > absolute interrupt ID, not a relative number based on the type.

    Hi Rob,

    See here[1] and [2] (figures 3.14 and 3.16). In both cases, there is
    clearly a reference to PPI numbering from 0-15 and SPI numbering from
    0-987 (as inputs to the distributor block).

    [1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0416b/Bhacbfdb.html
    [2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0416b/Cihebcbg.html

    g.


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