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dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from LY0PR12MB727857.namprd12.prod.outlook.com (2603:10b6:408:3ba::5) by SJ1PR12MB6339.namprd12.prod.outlook.com (2603:10b6:a03:454::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.546.15; Wed, 21 Oct 2026 23:10:49 +0000 Received: from LY0PR12MB727857.namprd12.prod.outlook.com ([fe80::843e:82cd:41ca:f522]) by LY0PR12MB727857.namprd12.prod.outlook.com ([fe80::843e:82cd:41ca:f522%5]) with mapi id 15.21.0546.012; Wed, 21 Oct 2026 23:10:49 +0000 Message-ID: <658ec783-75c7-4f06-9f92-b3c179e0f8bc@nvidia.com> Date: Wed, 21 Oct 2026 16:10:46 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/2] cache: add SMCCC-backed cache invalidate provider To: Andre Przywara , =?UTF-8?B?QmVuY2UgQ3PDs2vDoXM=?= , mark.rutland@arm.com, lpieralisi@kernel.org, sudeep.holla@kernel.org, conor@kernel.org, jic23@kernel.org Cc: catalin.marinas@arm.com, will@kernel.org, aneesh.kumar@kernel.org, Souvik.Chakravarty@arm.com, treding@nvidia.com, jonathanh@nvidia.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org References: <20261013070205.3566865-1-smadhavan@nvidia.com> <20261013070205.3566865-3-smadhavan@nvidia.com> <23e9b66f-083a-4a77-8214-25f30c08057a@arm.com> <03b070de-b0b0-44d9-89ce-891e6c3ac4d2@arm.com> Content-Language: en-US From: Srirangan Madhavan In-Reply-To: <03b070de-b0b0-44d9-89ce-891e6c3ac4d2@arm.com> Content-Type: text/plain; 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>>>> +    struct smccc_cache *cache; >>>> +    int ret; >>>> + >>>> +    arm_smccc_1_1_invoke(sdev->func_id, &res); >>> >>> I think you should provide the explicit function ID name here, and not >>> rely on which function exactly is used to probe for the interface's >>> existence. >> >> I thought that was the point of the matcher, that you could in theory > > But that probe() function here is not a "matcher" or a check function, > that is done in the SMCCC bus generic code, using a function ID that has > no side effects and does not return -1. > > The reason for this SMC call here is to learn the attributes, they are > used below to fill the latency and rate_limit fields in the struct. > So we should then make this explicit, I think, by using the > ARM_SMCCC_ARCH_CLEAN_INV_MEMREGION_ATTRIBUTES name. >> assign the same probe handler to any function ID? For example if there's >> some FW that implements this (or a compatible) function, but at a >> different ID, you would only update the match table? At least that's how >> most subsystems (I2C, PCI, USB) do it. > > Not sure I understand this, this is a driver specifically for the > CLEANINV_MEM_REGION SMCCC interface, I don't see how you would reuse > that, or plug any other interfaces to it. Thanks. The SMCCC bus has already performed the device matching before probe(), and this invocation is specifically used to retrieve the cache maintenance attributes. I changed this in v5 to use the explicit function ID. -- Regards, Srirangan