Message-ID: <348c3416-be44-b912-98ef-7f394bd408c0@linaro.org>
Date:   Fri, 27 Jan 2023 09:32:52 +0100
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Subject: Re: [RFC PATCH v2 02/31] Documentation: Add binding for
 kalray,kv3-1-core-intc
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To:     Jules Maselbas <jmaselbas@kalray.eu>
Cc:     Yann Sionneau <ysionneau@kalray.eu>, Arnd Bergmann <arnd@arndb.de>,
        Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Will Deacon <will@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Boqun Feng <boqun.feng@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Eric Biederman <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Waiman Long <longman@redhat.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nick Piggin <npiggin@gmail.com>,
        Paul Moore <paul@paul-moore.com>,
        Eric Paris <eparis@redhat.com>,
        Christian Brauner <brauner@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Guillaume Thouvenin <gthouvenin@kalray.eu>,
        Clement Leger <clement@clement-leger.fr>,
        Vincent Chardon <vincent.chardon@elsys-design.com>,
        =?UTF-8?Q?Marc_Poulhi=c3=a8s?= <dkm@kataplop.net>,
        Julian Vetter <jvetter@kalray.eu>,
        Samuel Jones <sjones@kalray.eu>,
        Ashley Lesdalons <alesdalons@kalray.eu>,
        Thomas Costis <tcostis@kalray.eu>,
        Marius Gligor <mgligor@kalray.eu>,
        Jonathan Borne <jborne@kalray.eu>,
        Julien Villette <jvillette@kalray.eu>,
        Luc Michel <lmichel@kalray.eu>,
        Louis Morhet <lmorhet@kalray.eu>,
        Julien Hascoet <jhascoet@kalray.eu>,
        Jean-Christophe Pince <jcpince@gmail.com>,
        Guillaume Missonnier <gmissonnier@kalray.eu>,
        Alex Michon <amichon@kalray.eu>,
        Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <git@xen0n.name>,
        Shaokun Zhang <zhangshaokun@hisilicon.com>,
        John Garry <john.garry@huawei.com>,
        Guangbin Huang <huangguangbin2@huawei.com>,
        Bharat Bhushan <bbhushan2@marvell.com>,
        Bibo Mao <maobibo@loongson.cn>,
        Atish Patra <atishp@atishpatra.org>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Qi Liu <liuqi115@huawei.com>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mark Brown <broonie@kernel.org>,
        Janosch Frank <frankja@linux.ibm.com>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Benjamin Mugnier <mugnier.benjamin@gmail.com>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-audit@redhat.com,
        linux-riscv@lists.infradead.org, bpf@vger.kernel.org
References: <20230120141002.2442-1-ysionneau@kalray.eu>
 <20230120141002.2442-3-ysionneau@kalray.eu>
 <d4d998ee-1532-c896-df25-195ec9c72e3f@linaro.org>
 <20230126161032.GH5952@tellis.lin.mbt.kalray.eu>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <20230126161032.GH5952@tellis.lin.mbt.kalray.eu>
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Precedence: bulk

On 26/01/2023 17:10, Jules Maselbas wrote:

>>> +  reg:
>>> +    maxItems: 0
>>
>> ??? No way... What's this?
> This (per CPU) interrupt controller is not memory mapped at all, it is
> controlled and configured through system registers.
> 
> I do not have found existing .yaml bindings for such devices, only the
> file snps,archs-intc.txt has something similar.
> 
> I do not know what is the best way to represent such devices in the
> device-tree.  Any suggestions are welcome.

You cannot have an array property with 0 items. How would it look like
in DTS? There are many, many bindings which are expressing it. Just drop
the reg.

> 
>>
>>> +  "kalray,intc-nr-irqs":
>>
>> Drop quotes.
>>
>>> +    description: Number of irqs handled by the controller.
>>
>> Why this is variable per board? Why do you need it ?
> This property is not even used in our device-tree, this will be removed
> from the documentation and from the driver as well.
> 
>>> +
>>> +required:
>>> +  - compatible
>>> +  - "#interrupt-cells"
>>> +  - interrupt-controller
>>
>> missing additionalProperties: false
>>
>> This binding looks poor, like you started from something odd. Please
>> don't. Take the newest reviewed binding or better example-schema and use
>> it to build yours. This would solve several trivial mistakes and style
>> issues.
> I am starting over from the example-schema.
> 
>>> +
>>> +examples:
>>> +  - |
>>> +    intc: interrupt-controller {
>>
>> What's the IO address space?
> As said above, this is not a memory mapped device, but is accessed
> through system registers.

Sure, but then you cannot define a reg which was confusing...

Best regards,
Krzysztof