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Message-ID: <Y/NMWZAW4KAqKXEs@wendy>
Date: Mon, 20 Feb 2023 10:32:57 +0000
From: Conor Dooley <conor.dooley@...rochip.com>
To: Anup Patel <apatel@...tanamicro.com>
CC: Conor Dooley <conor@...nel.org>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Thomas Gleixner <tglx@...utronix.de>,
Marc Zyngier <maz@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Atish Patra <atishp@...shpatra.org>,
Alistair Francis <Alistair.Francis@....com>,
Anup Patel <anup@...infault.org>,
<linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
<devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 6/9] dt-bindings: interrupt-controller: Add RISC-V
advanced PLIC
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@...nel.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@...tanamicro.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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