Re: [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:

quoted

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.