linux-kernel - Re: [PATCH 13/36] dt-bindings: arm: Convert PMU binding to json-schema

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Message-ID: <08738708-1c38-fab7-eb34-694e5f4d4b7e@arm.com>
Date:   Thu, 8 Nov 2018 15:54:31 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Rob Herring <robh@...nel.org>, Will Deacon <will.deacon@....com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Cc:     Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org,
        Kumar Gala <kumar.gala@...aro.org>,
        Grant Likely <glikely@...retlab.ca>,
        Arnd Bergmann <arnd@...db.de>, Tom Rini <trini@...sulko.com>,
        Frank Rowand <frowand.list@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Olof Johansson <olof@...om.net>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 13/36] dt-bindings: arm: Convert PMU binding to
 json-schema

On 01/11/2018 19:32, Rob Herring wrote:
> On Tue, Oct 9, 2018 at 6:57 AM Will Deacon <will.deacon@....com> wrote:
>>
>> Hi Rob,
>>
>> On Fri, Oct 05, 2018 at 11:58:25AM -0500, Rob Herring wrote:
>>> Convert ARM PMU binding to DT schema format using json-schema.
>>>
>>> Cc: Will Deacon <will.deacon@....com>
>>> Cc: Mark Rutland <mark.rutland@....com>
>>> Cc: linux-arm-kernel@...ts.infradead.org
>>> Cc: devicetree@...r.kernel.org
>>> Signed-off-by: Rob Herring <robh@...nel.org>
>>> ---
>>>   Documentation/devicetree/bindings/arm/pmu.txt | 70 --------------
>>>   .../devicetree/bindings/arm/pmu.yaml          | 96 +++++++++++++++++++
>>>   2 files changed, 96 insertions(+), 70 deletions(-)
>>>   delete mode 100644 Documentation/devicetree/bindings/arm/pmu.txt
>>>   create mode 100644 Documentation/devicetree/bindings/arm/pmu.yaml
>>
>> [...]
>>
>>> -- interrupts : 1 combined interrupt or 1 per core. If the interrupt is a per-cpu
>>> -               interrupt (PPI) then 1 interrupt should be specified.
>>
>> [...]
>>
>>> +  interrupts:
>>> +    oneOf:
>>> +      - maxItems: 1
>>> +      - minItems: 2
>>> +        maxItems: 8
>>> +        description: 1 interrupt per core.
>>> +
>>> +  interrupts-extended:
>>> +    $ref: '#/properties/interrupts'
>>
>> This seems like a semantic different between the two representations, or am
>> I missing something here? Specifically, both the introduction of
>> interrupts-extended and also dropping any mention of using a single per-cpu
>> interrupt (the single combined case is no longer support by Linux; not sure
>> if you want to keep it in the binding).
> 
> In regards to no support for the single combined interrupt, it looks
> like Marvell Armada SoCs at least (armada-375 is what I'm looking at)
> have only a single interrupt. Though the interrupt gets routed to MPIC
> which then has a GIC PPI. So it isn't supported or happens to work
> still since it is a PPI?

Well, the description of the MPIC in the Armada XP functional spec says:

"Interrupt sources ID0–ID28 are private events per CPU. Thus, each 
processor has a different set of events map interrupts ID0–ID28."

Odd grammar aside, that would seem to imply that <&mpic 3> is a per-cpu 
interrupt itself, thus AFAICS so long as it's cascaded to a GIC PPI and 
not an SPI then there's no issue there.

Robin.