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[109.252.170.211]) by smtp.googlemail.com with ESMTPSA id x5sm67196lfd.119.2020.09.29.22.59.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Sep 2020 22:59:46 -0700 (PDT) Subject: Re: [PATCH v2 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev To: Nicolin Chen Cc: thierry.reding@gmail.com, joro@8bytes.org, krzk@kernel.org, vdumpa@nvidia.com, jonathanh@nvidia.com, linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20200930003013.31289-1-nicoleotsuka@gmail.com> <20200930003013.31289-3-nicoleotsuka@gmail.com> <20200930054119.GE31821@Asurada-Nvidia> From: Dmitry Osipenko Message-ID: <68c13611-bc3d-5ba6-70ec-29786d69ff9a@gmail.com> Date: Wed, 30 Sep 2020 08:59:45 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200930054119.GE31821@Asurada-Nvidia> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org 30.09.2020 08:41, Nicolin Chen пишет: > On Wed, Sep 30, 2020 at 08:39:54AM +0300, Dmitry Osipenko wrote: >> 30.09.2020 03:30, Nicolin Chen пишет: >>> static int tegra_smmu_attach_dev(struct iommu_domain *domain, >>> struct device *dev) >>> { >>> + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); >>> struct tegra_smmu *smmu = dev_iommu_priv_get(dev); >>> struct tegra_smmu_as *as = to_smmu_as(domain); >>> - struct device_node *np = dev->of_node; >>> - struct of_phandle_args args; >>> unsigned int index = 0; >>> int err = 0; >>> >>> - while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index, >>> - &args)) { >>> - unsigned int swgroup = args.args[0]; >>> - >>> - if (args.np != smmu->dev->of_node) { >>> - of_node_put(args.np); >>> - continue; >>> - } >>> - >>> - of_node_put(args.np); >>> + if (!fwspec || fwspec->ops != &tegra_smmu_ops) >>> + return -ENOENT; >> >> s/&tegra_smmu_ops/smmu->iommu.ops/ >> >> Secondly, is it even possible that fwspec could be NULL here or that >> fwspec->ops != smmu->ops? > > I am following what's in the arm-smmu driver, as I think it'd be > a common practice to do such a check in such a way. > Please check whether it's really needed. It looks like it was needed sometime ago, but that's not true anymore.