Re: [PATCH v2 6/9] dt-bindings: interrupt-controller: Add RISC-V advanced PLIC

[Conor Dooley <conor.dooley@microchip.com>]

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Hey Anup,

On Mon, Feb 20, 2023 at 10:06:49AM +0530, Anup Patel wrote:
> On Thu, Jan 5, 2023 at 3:47 AM Conor Dooley <conor@kernel.org> wrote:
> > On Tue, Jan 03, 2023 at 07:44:06PM +0530, Anup Patel wrote:
> > > We add DT bindings document for RISC-V advanced platform level
> > > interrupt controller (APLIC) defined by the RISC-V advanced
> > > interrupt architecture (AIA) specification.
> > >
> > > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> > > ---
> > >  .../interrupt-controller/riscv,aplic.yaml     | 159 ++++++++++++++++++
> > >  1 file changed, 159 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/interrupt-controller/riscv,aplic.yaml

> > I'm sorry Anup, but this child versus delegate thing is still not clear
> > to me binding wise. See below.
> 
> There are two different information in-context of APLIC domain:
> 
> 1) HW child domain numbering: If an APLIC domain has N children
>     then HW will have a fixed child index for each of the N children
>     in the range 0 to N-1. This HW child index is required at the time
>     of setting up interrupt delegation in sourcecfgX registers. The
>     "riscv,children" DT property helps firmware (or bootloader) find
>     the total number of child APLIC domains and corresponding
>     HW child index number.
> 
> 2) IRQ delegation to child domains: An APLIC domain can delegate
>    any IRQ range(s) to a particular APLIC child domain. The
>    "riscv,delegate" DT property is simply a table where we have
>    one row for each IRQ range which is delegated to some child
>    APLIC domain. This property is more of a system setting fixed
>    by the RISC-V platform vendor.

Thanks for the explanations. It's been a while since my brain swapped
this stuff out, but I think delegate/child makes sense to me now.
Just don't ask me to write the dt entry as proof...

Thanks,
Conor.

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