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Tue, 30 Jun 2020 10:17:39 +0000 Subject: Re: [PATCH v8 1/3] iommu/arm-smmu: add NVIDIA implementation for dual ARM MMU-500 usage To: Krishna Reddy References: <20200630001051.12350-1-vdumpa@nvidia.com> <20200630001051.12350-2-vdumpa@nvidia.com> From: Jon Hunter Message-ID: Date: Tue, 30 Jun 2020 11:17:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200630001051.12350-2-vdumpa@nvidia.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) Content-Language: en-US DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1593512219; bh=BfZIPiMPzpjUihBsAJUP01sDidpTF7q6kK3zqhZ7zvI=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=OlRYIRuGOhccq3GHllo7CDUevA5/1z9P5ceHZ3yzGD8KsarRUGUXIN80yEiRHK5Us OdXTUZ2OzIV3KlL9VebsZEIEm1ILF852V/JnTdES6+E8hwyFMf9bpU2uns7SP4/8Kb /SIWsLU6EIe98bqfD/Uwlkjf0wF2liX+WCNEO9+P1FnBIl2oZjhQu01H18Kj3SLgE8 iUurpA47wuV7F+JlJlb0bav6z1grUoSWptSt01hQ+yVRKHa0cFoGlmihOH5eSNkSiE D80cjprdSxdGgGxNJH7eJy2c5NLkSw6jS1ci1ezFzxIMpLEcYMFEvYMLVcep1dhowz 7uE3EY8UQtZ7A== Cc: snikam@nvidia.com, nicoleotsuka@gmail.com, mperttunen@nvidia.com, bhuntsman@nvidia.com, will@kernel.org, linux-kernel@vger.kernel.org, praithatha@nvidia.com, talho@nvidia.com, iommu@lists.linux-foundation.org, nicolinc@nvidia.com, linux-tegra@vger.kernel.org, yhsu@nvidia.com, treding@nvidia.com, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org, bbiswas@nvidia.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 30/06/2020 01:10, Krishna Reddy wrote: > NVIDIA's Tegra194 SoC uses two ARM MMU-500s together to interleave > IOVA accesses across them. > Add NVIDIA implementation for dual ARM MMU-500s and add new compatible > string for Tegra194 SoC SMMU topology. > > Signed-off-by: Krishna Reddy > --- > MAINTAINERS | 2 + > drivers/iommu/Makefile | 2 +- > drivers/iommu/arm-smmu-impl.c | 3 + > drivers/iommu/arm-smmu-nvidia.c | 196 ++++++++++++++++++++++++++++++++ > drivers/iommu/arm-smmu.h | 1 + > 5 files changed, 203 insertions(+), 1 deletion(-) > create mode 100644 drivers/iommu/arm-smmu-nvidia.c ... > +struct arm_smmu_device *nvidia_smmu_impl_init(struct arm_smmu_device *smmu) > +{ > + unsigned int i; > + struct nvidia_smmu *nvidia_smmu; > + struct platform_device *pdev = to_platform_device(smmu->dev); > + > + nvidia_smmu = devm_kzalloc(smmu->dev, sizeof(*nvidia_smmu), GFP_KERNEL); > + if (!nvidia_smmu) > + return ERR_PTR(-ENOMEM); > + > + nvidia_smmu->smmu = *smmu; > + /* Instance 0 is ioremapped by arm-smmu.c after this function returns */ > + nvidia_smmu->num_inst = 1; > + > + for (i = 1; i < MAX_SMMU_INSTANCES; i++) { > + struct resource *res; > + > + res = platform_get_resource(pdev, IORESOURCE_MEM, i); > + if (!res) > + break; Currently this driver is only supported for Tegra194 which I understand has 3 SMMUs. Therefore, I don't feel that we should fail silently here, I think it is better to return an error if all 3 cannot be initialised. In the future if there is an SoC that has less (hopefully not more) than Tegra194 then we should handle this via the DT compatible string. In other words, we should always know how many SMMUs there are for a given SoC and how many we should initialise. > + > + nvidia_smmu->bases[i] = devm_ioremap_resource(smmu->dev, res); > + if (IS_ERR(nvidia_smmu->bases[i])) > + return ERR_CAST(nvidia_smmu->bases[i]); You want to use PTR_ERR() here. Jon -- nvpublic _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu