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[109.252.170.211]) by smtp.googlemail.com with ESMTPSA id q6sm176381ljg.115.2020.09.30.07.41.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Sep 2020 07:41:42 -0700 (PDT) Subject: Re: [PATCH v3 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev To: Nicolin Chen , thierry.reding@gmail.com, joro@8bytes.org, krzk@kernel.org Cc: vdumpa@nvidia.com, jonathanh@nvidia.com, linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20200930084258.25493-1-nicoleotsuka@gmail.com> <20200930084258.25493-3-nicoleotsuka@gmail.com> From: Dmitry Osipenko Message-ID: <01728f61-df0c-291d-5589-4468be25f00c@gmail.com> Date: Wed, 30 Sep 2020 17:41:42 +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: <20200930084258.25493-3-nicoleotsuka@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ... > + struct tegra_mc *mc = devm_tegra_get_memory_controller(dev); > + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); > > - of_node_put(args.np); > - index++; > - } > + /* An invalid mc pointer means mc and smmu drivers are not ready */ > + if (IS_ERR(mc)) > + return ERR_PTR(-EPROBE_DEFER); > > - if (!smmu) > + /* > + * IOMMU core allows -ENODEV return to carry on. So bypass any call > + * from bus_set_iommu() during tegra_smmu_probe(), as a device will > + * call in again via of_iommu_configure when fwspec is prepared. > + */ > + if (!mc->smmu || !fwspec || fwspec->ops != &tegra_smmu_ops) > return ERR_PTR(-ENODEV); > > - return &smmu->iommu; > + dev_iommu_priv_set(dev, mc->smmu); > + > + return &mc->smmu->iommu; > } Is it really okay to use devm_tegra_get_memory_controller() here? I assume it should be more preferred to do it only for devices that have fwspec->ops == &tegra_smmu_ops. Secondly, it also looks to me that a non-devm variant should be more appropriate here because tegra_smmu_probe_device() isn't invoked by the devices themselves.