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Fri, 23 Feb 2024 14:40:18 +0100 (CET) Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-ap.st.com (STMicroelectronics) with ESMTP id E9FE040044; Fri, 23 Feb 2024 14:40:13 +0100 (CET) Received: from Webmail-eu.st.com (shfdag1node1.st.com [10.75.129.69]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id DF21A29D7F4; Fri, 23 Feb 2024 14:39:26 +0100 (CET) Received: from [192.168.8.15] (10.201.20.114) by SHFDAG1NODE1.st.com (10.75.129.69) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Fri, 23 Feb 2024 14:39:26 +0100 Message-ID: <2eb11bf9dc0c5f49de3fb72c44dd16d8ca136813.camel@foss.st.com> Subject: Re: [PATCH 02/12] dt-bindings: interrupt-controller: stm32-exti: Add irq nexus child node From: Antonio Borneo To: Rob Herring CC: Thomas Gleixner , Krzysztof Kozlowski , Conor Dooley , Maxime Coquelin , Alexandre Torgue , Catalin Marinas , Will Deacon , , , , , Fabrice Gasnier Date: Fri, 23 Feb 2024 14:39:25 +0100 In-Reply-To: <20240222234300.GA3809915-robh@kernel.org> References: <20240216094758.916722-1-antonio.borneo@foss.st.com> <20240216094758.916722-3-antonio.borneo@foss.st.com> <20240222234300.GA3809915-robh@kernel.org> User-Agent: Evolution 3.48.4 MIME-Version: 1.0 X-Originating-IP: [10.201.20.114] X-ClientProxiedBy: SHFCAS1NODE1.st.com (10.75.129.72) To SHFDAG1NODE1.st.com (10.75.129.69) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-02-22_15,2024-02-23_01,2023-05-22_02 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240223_054052_684661_255EB8EC X-CRM114-Status: GOOD ( 22.19 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 2024-02-22 at 16:43 -0700, Rob Herring wrote: > On Fri, Feb 16, 2024 at 10:47:47AM +0100, Antonio Borneo wrote: > > The mapping of EXTI interrupts to its parent interrupt controller > > is both SoC and instance dependent. > > The current implementation requires adding a new table to the > > driver's code and a new compatible for each new EXTI instance. > > > > Add to the binding an interrupt nexus child node that will be > > used on the new EXTI instances and can be optionally used on the > > existing instances. > > The property 'interrupt-map' in the nexus node maps each EXTI > > interrupt to the parent interrupt. > > Align #address-cells and #interrupt-cells between the EXTI node > > and its nexus node. > > Looks like an abuse of interrupt-map. You avoid adding yourself to the > abuser list by putting it in a child node. Clever. (See list in > drivers/of/irq.c if you don't know what I'm talking about) Hi Rob, thanks for the review. Yes, I know already about the abuser list but, from the commit message and the associated comment, I interpret it as an incorrect use of the property interrupt-map with custom syntax thus relying on custom parsing code. The child nexus node in this series allows using the default parser in kernel. >From your reply, looks like my interpretation is incorrect and I missed the real concern about the abuser list. Could you please explain why this use of interrupt-map is incorrect and/or which are the correct use cases? > I assume the EXTI has 0..N interrupts. Just define 'interrupts' with N > entries with each entry mapping EXTI interrupt N to 'interrupts' entry > N. Yes, EXTI has 0..N interrupts that can be mapped to multiple parent interrupt controllers and the mapping table has holes. While the DT in this series only use one interrupt parent, a second parent will follow. So 'interrupts-extended' property would be a better matching than 'interrupts' to handle the multiple parents. But how to code the missing entries in an 'interrupts-extended' list? As in the example in Documentation/devicetree/bindings/dma/apple,admac.yaml ? The 'interrupt-map' contains the matching EXTI index, thus allowing a 'sparse' map where holes are simply ignored. Best Regards, Antonio _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel