linux-kernel - Re: [PATCH] dt-bindings: irqchip: Add #address-cells to PRUSS INTC

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Message-ID: <23225695-57ea-f255-798b-17cf6962e543@ti.com>
Date:   Tue, 26 Jan 2021 09:54:46 -0600
From:   Suman Anna <s-anna@...com>
To:     Rob Herring <robh@...nel.org>
CC:     Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Nishanth Menon <nm@...com>, Lokesh Vutla <lokeshvutla@...com>,
        Sekhar Nori <nsekhar@...com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        David Lechner <david@...hnology.com>,
        <devicetree@...r.kernel.org>,
        linux-omap <linux-omap@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
Subject: Re: [PATCH] dt-bindings: irqchip: Add #address-cells to PRUSS INTC

Hi Rob,

On 1/25/21 8:47 PM, Rob Herring wrote:
> On Mon, Jan 25, 2021 at 6:16 PM Suman Anna <s-anna@...com> wrote:
>>
>> Hi Rob,
>>
>> On 1/25/21 6:04 PM, Rob Herring wrote:
>>> On Fri, Jan 15, 2021 at 02:58:19PM -0600, Suman Anna wrote:
>>>> The '#address-cells' property looks to be a required property for
>>>> interrupt controller nodes as indicated by a warning message seen
>>>> when building dtbs with W=2. Adding the property to the PRUSS INTC
>>>> dts nodes though fails the dtbs_check. Add this property to the
>>>> PRUSS INTC binding to make it compliant with both dtbs_check and
>>>> building dtbs.
>>>>
>>>> Signed-off-by: Suman Anna <s-anna@...com>
>>>> ---
>>>> Hi Rob,
>>>>
>>>> This patch is also part of our effort to get rid of the warnings seen
>>>> around interrupt providers on TI K3 dtbs [1]. I needed this in the PRUSS
>>>> INTC bindings to not get a warning with dtbs_check while also ensuring
>>>> no warnings while building dtbs with W=2.
>>>>
>>>> I would have expected the '#address-cells' requirement to be inherited
>>>> automatically. And looking through the schema files, I actually do not
>>>> see the interrupt-controller.yaml included automatically anywhere. You
>>>> had asked us to drop the inclusion in this binding in our first version
>>>> with YAML [3]. Am I missing something, and how do we ensure that this
>>>> is enforced automatically for everyone?
>>>
>>> interrupt-controller.yaml is applied to any node named
>>> 'interrupt-controller'. More generally, if 'compatible' is not present,
>>> then we look at $nodename for the default 'select'. In your case, you
>>> didn't name the node appropriately.
>>
>> Thanks for the clarification. Yeah, I didn't add anything specifically, since
>> the expectation is interrupt-controller. Should I be adding that to this binding?
> 
> No, either interrupt-controller.yaml needs to learn a new node name or
> your node names need to be fixed. I prefer the latter, but if you have
> more than 1 and don't have a unit-address (and in turn a 'reg' prop)
> we'd have to do the former. How are the interrupts controllers
> accessed if there's no way to address them?

The PRUSS INTC will always have a unit-address, so we won't have the issues with
having to maintain unique names. All my examples already have the nodes in the
form 'interrupt-controller@<addr>'. Anyway, I will drop this patch, and post a
new patch adding the $nodename to the binding.

> 
>>
>>>
>>> We can't check this in interrupt-controller.yaml because #address-cells
>>> is not always 0. GICv3 is one notable exception.
>>>
>>>>
>>>> regards
>>>> Suman
>>>>
>>>> [1] https://patchwork.kernel.org/project/linux-arm-kernel/patch/20210115083003.27387-1-lokeshvutla@ti.com/
>>>
>>> I've commented on this thread now in regards to #address-cells.
>>
>> I suppose I still need this patch to be defined to unblock the ICSSG nodes
>> getting accepted by our dts maintainer. Care to give your Reviewed-by for the
>> change? Or I can spin a v2 with $nodename added as well if that's needed too.
> 
> No, I don't think you have to add #address-cells. We need to fix the
> warning in dtc.

Thank you for clarifying this.

regards
Suman